Obama’s change of mind had its origins at Porton Down, the defence laboratory in Wiltshire. British intelligence had obtained a sample of the sarin used in the 21 August attack and analysis demonstrated that the gas used didn’t match the batches known to exist in the Syrian army’s chemical weapons arsenal. The message that the case against Syria wouldn’t hold up was quickly relayed to the US joint chiefs of staff. The British report heightened doubts inside the Pentagon; the joint chiefs were already preparing to warn Obama that his plans for a far-reaching bomb and missile attack on Syria’s infrastructure could lead to a wider war in the Middle East. As a consequence the American officers delivered a last-minute caution to the president, which, in their view, eventually led to his cancelling the attack.

For months there had been acute concern among senior military leaders and the intelligence community about the role in the war of Syria’s neighbours, especially Turkey. Prime Minister Recep Erdoğan was known to be supporting the al-Nusra Front, a jihadist faction among the rebel opposition, as well as other Islamist rebel groups. ‘We knew there were some in the Turkish government,’ a former senior US intelligence official, who has access to current intelligence, told me, ‘who believed they could get Assad’s nuts in a vice by dabbling with a sarin attack inside Syria – and forcing Obama to make good on his red line threat.’

The joint chiefs also knew that the Obama administration’s public claims that only the Syrian army had access to sarin were wrong. The American and British intelligence communities had been aware since the spring of 2013 that some rebel units in Syria were developing chemical weapons. On 20 June analysts for the US Defense Intelligence Agency issued a highly classified five-page ‘talking points’ briefing for the DIA’s deputy director, David Shedd, which stated that al-Nusra maintained a sarin production cell: its programme, the paper said, was ‘the most advanced sarin plot since al-Qaida’s pre-9/11 effort’. (According to a Defense Department consultant, US intelligence has long known that al-Qaida experimented with chemical weapons, and has a video of one of its gas experiments with dogs.)

The DIA paper went on: ‘Previous IC [intelligence community] focus had been almost entirely on Syrian CW [chemical weapons] stockpiles; now we see ANF attempting to make its own CW … Al-Nusrah Front’s relative freedom of operation within Syria leads us to assess the group’s CW aspirations will be difficult to disrupt in the future.’ The paper drew on classified intelligence from numerous agencies: ‘Turkey and Saudi-based chemical facilitators,’ it said, ‘were attempting to obtain sarin precursors in bulk, tens of kilograms, likely for the anticipated large scale production effort in Syria.’ (Asked about the DIA paper, a spokesperson for the director of national intelligence said: ‘No such paper was ever requested or produced by intelligence community analysts.’)

Last May, more than ten members of the al-Nusra Front were arrested in southern Turkey with what local police told the press were two kilograms of sarin. In a 130-page indictment the group was accused of attempting to purchase fuses, piping for the construction of mortars, and chemical precursors for sarin. Five of those arrested were freed after a brief detention. The others, including the ringleader, Haytham Qassab, for whom the prosecutor requested a prison sentence of 25 years, were released pending trial. In the meantime the Turkish press has been rife with speculation that the Erdoğan administration has been covering up the extent of its involvement with the rebels. In a news conference last summer, Aydin Sezgin, Turkey’s ambassador to Moscow, dismissed the arrests and claimed to reporters that the recovered ‘sarin’ was merely ‘anti-freeze’.

The DIA paper took the arrests as evidence that al-Nusra was expanding its access to chemical weapons. It said Qassab had ‘self-identified’ as a member of al-Nusra, and that he was directly connected to Abd-al-Ghani, the ‘ANF emir for military manufacturing’. Qassab and his associate Khalid Ousta worked with Halit Unalkaya, an employee of a Turkish firm called Zirve Export, who provided ‘price quotes for bulk quantities of sarin precursors’. Abd-al-Ghani’s plan was for two associates to ‘perfect a process for making sarin, then go to Syria to train others to begin large scale production at an unidentified lab in Syria’. The DIA paper said that one of his operatives had purchased a precursor on the ‘Baghdad chemical market’, which ‘has supported at least seven CW efforts since 2004’.

A series of chemical weapon attacks in March and April 2013 was investigated over the next few months by a special UN mission to Syria. A person with close knowledge of the UN’s activity in Syria told me that there was evidence linking the Syrian opposition to the first gas attack, on 19 March in Khan Al-Assal, a village near Aleppo. In its final report in December, the mission said that at least 19 civilians and one Syrian soldier were among the fatalities, along with scores of injured. It had no mandate to assign responsibility for the attack, but the person with knowledge of the UN’s activities said: ‘Investigators interviewed the people who were there, including the doctors who treated the victims. It was clear that the rebels used the gas. It did not come out in public because no one wanted to know.’

In the months before the attacks began, a former senior Defense Department official told me, the DIA was circulating a daily classified report known as SYRUP on all intelligence related to the Syrian conflict, including material on chemical weapons. But in the spring, distribution of the part of the report concerning chemical weapons was severely curtailed on the orders of Denis McDonough, the White House chief of staff. ‘Something was in there that triggered a shit fit by McDonough,’ the former Defense Department official said. ‘One day it was a huge deal, and then, after the March and April sarin attacks’ – he snapped his fingers – ‘it’s no longer there.’ The decision to restrict distribution was made as the joint chiefs ordered intensive contingency planning for a possible ground invasion of Syria whose primary objective would be the elimination of chemical weapons.

The former intelligence official said that many in the US national security establishment had long been troubled by the president’s red line: ‘The joint chiefs asked the White House, “What does red line mean? How does that translate into military orders? Troops on the ground? Massive strike? Limited strike?” They tasked military intelligence to study how we could carry out the threat. They learned nothing more about the president’s reasoning.’

In the aftermath of the 21 August attack Obama ordered the Pentagon to draw up targets for bombing. Early in the process, the former intelligence official said, ‘the White House rejected 35 target sets provided by the joint chiefs of staff as being insufficiently “painful” to the Assad regime.’ The original targets included only military sites and nothing by way of civilian infrastructure. Under White House pressure, the US attack plan evolved into ‘a monster strike’: two wings of B-52 bombers were shifted to airbases close to Syria, and navy submarines and ships equipped with Tomahawk missiles were deployed. ‘Every day the target list was getting longer,’ the former intelligence official told me. ‘The Pentagon planners said we can’t use only Tomahawks to strike at Syria’s missile sites because their warheads are buried too far below ground, so the two B-52 air wings with two-thousand pound bombs were assigned to the mission. Then we’ll need standby search-and-rescue teams to recover downed pilots and drones for target selection. It became huge.’ The new target list was meant to ‘completely eradicate any military capabilities Assad had’, the former intelligence official said. The core targets included electric power grids, oil and gas depots, all known logistic and weapons depots, all known command and control facilities, and all known military and intelligence buildings.

Britain and France were both to play a part. On 29 August, the day Parliament voted against Cameron’s bid to join the intervention, the Guardian reported that he had already ordered six RAF Typhoon fighter jets to be deployed to Cyprus, and had volunteered a submarine capable of launching Tomahawk missiles. The French air force – a crucial player in the 2011 strikes on Libya – was deeply committed, according to an account in Le Nouvel Observateur; François Hollande had ordered several Rafale fighter-bombers to join the American assault. Their targets were reported to be in western Syria.

By the last days of August the president had given the Joint Chiefs a fixed deadline for the launch. ‘H hour was to begin no later than Monday morning [2 September], a massive assault to neutralise Assad,’ the former intelligence official said. So it was a surprise to many when during a speech in the White House Rose Garden on 31 August Obama said that the attack would be put on hold, and he would turn to Congress and put it to a vote.

At this stage, Obama’s premise – that only the Syrian army was capable of deploying sarin – was unravelling. Within a few days of the 21 August attack, the former intelligence official told me, Russian military intelligence operatives had recovered samples of the chemical agent from Ghouta. They analysed it and passed it on to British military intelligence; this was the material sent to Porton Down. (A spokesperson for Porton Down said: ‘Many of the samples analysed in the UK tested positive for the nerve agent sarin.’ MI6 said that it doesn’t comment on intelligence matters.)

The former intelligence official said the Russian who delivered the sample to the UK was ‘a good source – someone with access, knowledge and a record of being trustworthy’. After the first reported uses of chemical weapons in Syria last year, American and allied intelligence agencies ‘made an effort to find the answer as to what if anything, was used – and its source’, the former intelligence official said. ‘We use data exchanged as part of the Chemical Weapons Convention. The DIA’s baseline consisted of knowing the composition of each batch of Soviet-manufactured chemical weapons. But we didn’t know which batches the Assad government currently had in its arsenal. Within days of the Damascus incident we asked a source in the Syrian government to give us a list of the batches the government currently had. This is why we could confirm the difference so quickly.’

The process hadn’t worked as smoothly in the spring, the former intelligence official said, because the studies done by Western intelligence ‘were inconclusive as to the type of gas it was. The word “sarin” didn’t come up. There was a great deal of discussion about this, but since no one could conclude what gas it was, you could not say that Assad had crossed the president’s red line.’ By 21 August, the former intelligence official went on, ‘the Syrian opposition clearly had learned from this and announced that “sarin” from the Syrian army had been used, before any analysis could be made, and the press and White House jumped at it. Since it now was sarin, “It had to be Assad.”’

The UK defence staff who relayed the Porton Down findings to the joint chiefs were sending the Americans a message, the former intelligence official said: ‘We’re being set up here.’ (This account made sense of a terse message a senior official in the CIA sent in late August: ‘It was not the result of the current regime. UK & US know this.’) By then the attack was a few days away and American, British and French planes, ships and submarines were at the ready.

The officer ultimately responsible for the planning and execution of the attack was General Martin Dempsey, chairman of the joint chiefs. From the beginning of the crisis, the former intelligence official said, the joint chiefs had been sceptical of the administration’s argument that it had the facts to back up its belief in Assad’s guilt. They pressed the DIA and other agencies for more substantial evidence. ‘There was no way they thought Syria would use nerve gas at that stage, because Assad was winning the war,’ the former intelligence official said. Dempsey had irritated many in the Obama administration by repeatedly warning Congress over the summer of the danger of American military involvement in Syria. Last April, after an optimistic assessment of rebel progress by the secretary of state, John Kerry, in front of the House Foreign Affairs Committee, Dempsey told the Senate Armed Services Committee that ‘there’s a risk that this conflict has become stalemated.’

Dempsey’s initial view after 21 August was that a US strike on Syria – under the assumption that the Assad government was responsible for the sarin attack – would be a military blunder, the former intelligence official said. The Porton Down report caused the joint chiefs to go to the president with a more serious worry: that the attack sought by the White House would be an unjustified act of aggression. It was the joint chiefs who led Obama to change course. The official White House explanation for the turnabout – the story the press corps told – was that the president, during a walk in the Rose Garden with Denis McDonough, his chief of staff, suddenly decided to seek approval for the strike from a bitterly divided Congress with which he’d been in conflict for years. The former Defense Department official told me that the White House provided a different explanation to members of the civilian leadership of the Pentagon: the bombing had been called off because there was intelligence ‘that the Middle East would go up in smoke’ if it was carried out.

The president’s decision to go to Congress was initially seen by senior aides in the White House, the former intelligence official said, as a replay of George W. Bush’s gambit in the autumn of 2002 before the invasion of Iraq: ‘When it became clear that there were no WMD in Iraq, Congress, which had endorsed the Iraqi war, and the White House both shared the blame and repeatedly cited faulty intelligence. If the current Congress were to vote to endorse the strike, the White House could again have it both ways – wallop Syria with a massive attack and validate the president’s red line commitment, while also being able to share the blame with Congress if it came out that the Syrian military wasn’t behind the attack.’ The turnabout came as a surprise even to the Democratic leadership in Congress. In September the Wall Street Journal reported that three days before his Rose Garden speech Obama had telephoned Nancy Pelosi, leader of the House Democrats, ‘to talk through the options’. She later told colleagues, according to the Journal, that she hadn’t asked the president to put the bombing to a congressional vote.

Obama’s move for congressional approval quickly became a dead end. ‘Congress was not going to let this go by,’ the former intelligence official said. ‘Congress made it known that, unlike the authorisation for the Iraq war, there would be substantive hearings.’ At this point, there was a sense of desperation in the White House, the former intelligence official said. ‘And so out comes Plan B. Call off the bombing strike and Assad would agree to unilaterally sign the chemical warfare treaty and agree to the destruction of all of chemical weapons under UN supervision.’ At a press conference in London on 9 September, Kerry was still talking about intervention: ‘The risk of not acting is greater than the risk of acting.’ But when a reporter asked if there was anything Assad could do to stop the bombing, Kerry said: ‘Sure. He could turn over every single bit of his chemical weapons to the international community in the next week … But he isn’t about to do it, and it can’t be done, obviously.’ As the New York Times reported the next day, the Russian-brokered deal that emerged shortly afterwards had first been discussed by Obama and Putin in the summer of 2012. Although the strike plans were shelved, the administration didn’t change its public assessment of the justification for going to war. ‘There is zero tolerance at that level for the existence of error,’ the former intelligence official said of the senior officials in the White House. ‘They could not afford to say: “We were wrong.”’ (The DNI spokesperson said: ‘The Assad regime, and only the Assad regime, could have been responsible for the chemical weapons attack that took place on 21 August.’)

The full extent of US co-operation with Turkey, Saudi Arabia and Qatar in assisting the rebel opposition in Syria has yet to come to light. The Obama administration has never publicly admitted to its role in creating what the CIA calls a ‘rat line’, a back channel highway into Syria. The rat line, authorised in early 2012, was used to funnel weapons and ammunition from Libya via southern Turkey and across the Syrian border to the opposition. Many of those in Syria who ultimately received the weapons were jihadists, some of them affiliated with al-Qaida. (The DNI spokesperson said: ‘The idea that the United States was providing weapons from Libya to anyone is false.’)

In January, the Senate Intelligence Committee released a report on the assault by a local militia in September 2012 on the American consulate and a nearby undercover CIA facility in Benghazi, which resulted in the death of the US ambassador, Christopher Stevens, and three others. The report’s criticism of the State Department for not providing adequate security at the consulate, and of the intelligence community for not alerting the US military to the presence of a CIA outpost in the area, received front-page coverage and revived animosities in Washington, with Republicans accusing Obama and Hillary Clinton of a cover-up. A highly classified annex to the report, not made public, described a secret agreement reached in early 2012 between the Obama and Erdoğan administrations. It pertained to the rat line. By the terms of the agreement, funding came from Turkey, as well as Saudi Arabia and Qatar; the CIA, with the support of MI6, was responsible for getting arms from Gaddafi’s arsenals into Syria. A number of front companies were set up in Libya, some under the cover of Australian entities. Retired American soldiers, who didn’t always know who was really employing them, were hired to manage procurement and shipping. The operation was run by David Petraeus, the CIA director who would soon resign when it became known he was having an affair with his biographer. (A spokesperson for Petraeus denied the operation ever took place.)

The operation had not been disclosed at the time it was set up to the congressional intelligence committees and the congressional leadership, as required by law since the 1970s. The involvement of MI6 enabled the CIA to evade the law by classifying the mission as a liaison operation. The former intelligence official explained that for years there has been a recognised exception in the law that permits the CIA not to report liaison activity to Congress, which would otherwise be owed a finding. (All proposed CIA covert operations must be described in a written document, known as a ‘finding’, submitted to the senior leadership of Congress for approval.) Distribution of the annex was limited to the staff aides who wrote the report and to the eight ranking members of Congress – the Democratic and Republican leaders of the House and Senate, and the Democratic and Republicans leaders on the House and Senate intelligence committees. This hardly constituted a genuine attempt at oversight: the eight leaders are not known to gather together to raise questions or discuss the secret information they receive.

The annex didn’t tell the whole story of what happened in Benghazi before the attack, nor did it explain why the American consulate was attacked. ‘The consulate’s only mission was to provide cover for the moving of arms,’ the former intelligence official, who has read the annex, said. ‘It had no real political role.’

Washington abruptly ended the CIA’s role in the transfer of arms from Libya after the attack on the consulate, but the rat line kept going. ‘The United States was no longer in control of what the Turks were relaying to the jihadists,’ the former intelligence official said. Within weeks, as many as forty portable surface-to-air missile launchers, commonly known as manpads, were in the hands of Syrian rebels. On 28 November 2012, Joby Warrick of the Washington Post reported that the previous day rebels near Aleppo had used what was almost certainly a manpad to shoot down a Syrian transport helicopter. ‘The Obama administration,’ Warrick wrote, ‘has steadfastly opposed arming Syrian opposition forces with such missiles, warning that the weapons could fall into the hands of terrorists and be used to shoot down commercial aircraft.’ Two Middle Eastern intelligence officials fingered Qatar as the source, and a former US intelligence analyst speculated that the manpads could have been obtained from Syrian military outposts overrun by the rebels. There was no indication that the rebels’ possession of manpads was likely the unintended consequence of a covert US programme that was no longer under US control.

There was no public sign of discord when Erdoğan and Obama met on 16 May 2013 at the White House. At a later press conference Obama said that they had agreed that Assad ‘needs to go’. Asked whether he thought Syria had crossed the red line, Obama acknowledged that there was evidence such weapons had been used, but added, ‘it is important for us to make sure that we’re able to get more specific information about what exactly is happening there.’ The red line was still intact.

An American foreign policy expert who speaks regularly with officials in Washington and Ankara told me about a working dinner Obama held for Erdoğan during his May visit. The meal was dominated by the Turks’ insistence that Syria had crossed the red line and their complaints that Obama was reluctant to do anything about it. Obama was accompanied by John Kerry and Tom Donilon, the national security adviser who would soon leave the job. Erdoğan was joined by Ahmet Davutoğlu, Turkey’s foreign minister, and Hakan Fidan, the head of the MIT. Fidan is known to be fiercely loyal to Erdoğan, and has been seen as a consistent backer of the radical rebel opposition in Syria.

The foreign policy expert told me that the account he heard originated with Donilon. (It was later corroborated by a former US official, who learned of it from a senior Turkish diplomat.) According to the expert, Erdoğan had sought the meeting to demonstrate to Obama that the red line had been crossed, and had brought Fidan along to state the case. When Erdoğan tried to draw Fidan into the conversation, and Fidan began speaking, Obama cut him off and said: ‘We know.’ Erdoğan tried to bring Fidan in a second time, and Obama again cut him off and said: ‘We know.’ At that point, an exasperated Erdoğan said, ‘But your red line has been crossed!’ and, the expert told me, ‘Donilon said Erdoğan “fucking waved his finger at the president inside the White House”.’ Obama then pointed at Fidan and said: ‘We know what you’re doing with the radicals in Syria.’ (Donilon, who joined the Council on Foreign Relations last July, didn’t respond to questions about this story. The Turkish Foreign Ministry didn’t respond to questions about the dinner. A spokesperson for the National Security Council confirmed that the dinner took place and provided a photograph showing Obama, Kerry, Donilon, Erdoğan, Fidan and Davutoğlu sitting at a table. ‘Beyond that,’ she said, ‘I’m not going to read out the details of their discussions.’)

But Erdoğan did not leave empty handed. Obama was still permitting Turkey to continue to exploit a loophole in a presidential executive order prohibiting the export of gold to Iran, part of the US sanctions regime against the country. In March 2012, responding to sanctions of Iranian banks by the EU, the SWIFT electronic payment system, which facilitates cross-border payments, expelled dozens of Iranian financial institutions, severely restricting the country’s ability to conduct international trade. The US followed with the executive order in July, but left what came to be known as a ‘golden loophole’: gold shipments to private Iranian entities could continue. Turkey is a major purchaser of Iranian oil and gas, and it took advantage of the loophole by depositing its energy payments in Turkish lira in an Iranian account in Turkey; these funds were then used to purchase Turkish gold for export to confederates in Iran. Gold to the value of $13 billion reportedly entered Iran in this way between March 2012 and July 2013.

The programme quickly became a cash cow for corrupt politicians and traders in Turkey, Iran and the United Arab Emirates. ‘The middlemen did what they always do,’ the former intelligence official said. ‘Take 15 per cent. The CIA had estimated that there was as much as two billion dollars in skim. Gold and Turkish lira were sticking to fingers.’ The illicit skimming flared into a public ‘gas for gold’ scandal in Turkey in December, and resulted in charges against two dozen people, including prominent businessmen and relatives of government officials, as well as the resignations of three ministers, one of whom called for Erdoğan to resign. The chief executive of a Turkish state-controlled bank that was in the middle of the scandal insisted that more than $4.5 million in cash found by police in shoeboxes during a search of his home was for charitable donations.

Late last year Jonathan Schanzer and Mark Dubowitz reported in Foreign Policy that the Obama administration closed the golden loophole in January 2013, but ‘lobbied to make sure the legislation … did not take effect for six months’. They speculated that the administration wanted to use the delay as an incentive to bring Iran to the bargaining table over its nuclear programme, or to placate its Turkish ally in the Syrian civil war. The delay permitted Iran to ‘accrue billions of dollars more in gold, further undermining the sanctions regime’.

The American decision to end CIA support of the weapons shipments into Syria left Erdoğan exposed politically and militarily. ‘One of the issues at that May summit was the fact that Turkey is the only avenue to supply the rebels in Syria,’ the former intelligence official said. ‘It can’t come through Jordan because the terrain in the south is wide open and the Syrians are all over it. And it can’t come through the valleys and hills of Lebanon – you can’t be sure who you’d meet on the other side.’ Without US military support for the rebels, the former intelligence official said, ‘Erdoğan’s dream of having a client state in Syria is evaporating and he thinks we’re the reason why. When Syria wins the war, he knows the rebels are just as likely to turn on him – where else can they go? So now he will have thousands of radicals in his backyard.’

A US intelligence consultant told me that a few weeks before 21 August he saw a highly classified briefing prepared for Dempsey and the defense secretary, Chuck Hagel, which described ‘the acute anxiety’ of the Erdoğan administration about the rebels’ dwindling prospects. The analysis warned that the Turkish leadership had expressed ‘the need to do something that would precipitate a US military response’. By late summer, the Syrian army still had the advantage over the rebels, the former intelligence official said, and only American air power could turn the tide. In the autumn, the former intelligence official went on, the US intelligence analysts who kept working on the events of 21 August ‘sensed that Syria had not done the gas attack. But the 500 pound gorilla was, how did it happen? The immediate suspect was the Turks, because they had all the pieces to make it happen.’

As intercepts and other data related to the 21 August attacks were gathered, the intelligence community saw evidence to support its suspicions. ‘We now know it was a covert action planned by Erdoğan’s people to push Obama over the red line,’ the former intelligence official said. ‘They had to escalate to a gas attack in or near Damascus when the UN inspectors’ – who arrived in Damascus on 18 August to investigate the earlier use of gas – ‘were there. The deal was to do something spectacular. Our senior military officers have been told by the DIA and other intelligence assets that the sarin was supplied through Turkey – that it could only have gotten there with Turkish support. The Turks also provided the training in producing the sarin and handling it.’ Much of the support for that assessment came from the Turks themselves, via intercepted conversations in the immediate aftermath of the attack. ‘Principal evidence came from the Turkish post-attack joy and back-slapping in numerous intercepts. Operations are always so super-secret in the planning but that all flies out the window when it comes to crowing afterwards. There is no greater vulnerability than in the perpetrators claiming credit for success.’ Erdoğan’s problems in Syria would soon be over: ‘Off goes the gas and Obama will say red line and America is going to attack Syria, or at least that was the idea. But it did not work out that way.’

The post-attack intelligence on Turkey did not make its way to the White House. ‘Nobody wants to talk about all this,’ the former intelligence official told me. ‘There is great reluctance to contradict the president, although no all-source intelligence community analysis supported his leap to convict. There has not been one single piece of additional evidence of Syrian involvement in the sarin attack produced by the White House since the bombing raid was called off. My government can’t say anything because we have acted so irresponsibly. And since we blamed Assad, we can’t go back and blame Erdoğan.’

Turkey’s willingness to manipulate events in Syria to its own purposes seemed to be demonstrated late last month, a few days before a round of local elections, when a recording, allegedly of a government national security meeting, was posted to YouTube. It included discussion of a false-flag operation that would justify an incursion by the Turkish military in Syria. The operation centred on the tomb of Suleyman Shah, the grandfather of the revered Osman I, founder of the Ottoman Empire, which is near Aleppo and was ceded to Turkey in 1921, when Syria was under French rule. One of the Islamist rebel factions was threatening to destroy the tomb as a site of idolatry, and the Erdoğan administration was publicly threatening retaliation if harm came to it. According to a Reuters report of the leaked conversation, a voice alleged to be Fidan’s spoke of creating a provocation: ‘Now look, my commander, if there is to be justification, the justification is I send four men to the other side. I get them to fire eight missiles into empty land [in the vicinity of the tomb]. That’s not a problem. Justification can be created.’ The Turkish government acknowledged that there had been a national security meeting about threats emanating from Syria, but said the recording had been manipulated. The government subsequently blocked public access to YouTube.

Letter from MIT weapons experts in refutation of criticism of Hersh’s claims. Full link to original letters at the end of this piece:

Jamie Allinson makes some false technical claims in his critique of Seymour Hersh (Letters, 8 May). What Hersh reports is entirely plausible, and consistent with facts that emerged from our more limited but irrefutable technical studies of the circumstances surrounding the nerve agent attack in Damascus on 21 August 2013. Our findings, which have become the basis for the ‘new’ arguments being made against Hersh by people like Allinson, and supposedly knowledgeable non-government organisations like Human Rights Watch and the New York Times, raise the most serious questions about whether the White House lied about technical intelligence associated with the attack.