The US has finally confirmed what the UK and Europe have long regarded as clear: that the Syrian government has used chemical weapons against the rebels and that President Obama's famous "red line" has been crossed.
"Following a deliberative review our intelligence community assesses that the Assad regime has used chemical weapons, including the nerve agent sarin, on a small scale against the opposition multiple times in the last year," said the White House's statement.
"Our intelligence community has high confidence in that assessment given multiple, independent streams of information. The intelligence community estimates that 100 to 150 people have died from detected chemical weapons attacks in Syria to date; however, casualty data is likely incomplete."
After this statement, deputy national security adviser Ben Rhodes announced that the US would provide "further support" to the opposition's Supreme Military Council, including "military support". The language was deliberately opaque. Was Rhodes referring to non-lethal equipment such as vehicles, communications and body armour, or was he referring to military arms? "I can't detail what type of support yet" was his response. But judging by reports from the US media, the answer is the latter. The New York Times states that the administration has decided to supply the rebels with "small arms and ammunition", describing it as "lethal aid". It's also notable that while playing down reports that a no-fly zone is set to be established on the Jordanian border, Rhodes said nothing to rule out this option.
All of which means that it is now decision time for David Cameron. After succeeding in lifting the EU arms embargo, Cameron insisted at PMQs this week that the government "had not made a decision to supply the Syrian opposition with weapons", adding that it was providing "assistance, advice and technical help". When Ed Miliband pressed him on what "safeguards" were in place should lethal equipment be supplied, he again declared: "we are not supplying the opposition with weapons. We are supplying them with technical assistance and non-lethal equipment."
But the US decision to supply "lethal aid" means that the Prime Minister can no longer remain on the fence. On the Today programme this morning, Conservative MP John Baron, one of many sceptics on the Tory benches, declared that "we don't have to follow the US". The question for Cameron, who has all but confirmed that the Commons will be given a vote on arming the rebels, is whether we will.