The American and British governments should have seen this coming.
Having suddenly decided that military action was a strong probability - after two years of avoiding entanglement in Syria - they late last week began sucking up intelligence on the chemical weapons attack in Damascus.
Senior officials - Joe Biden, John Kerry, William Hague - began "building the case" for a military intervention through statements of certainty. In a matter of days the momentum was such that air strikes against Damascus were being referred to by government sources as likely by "mid-week" or "weekend at the latest".
The timetable appeared to be running to an artificial Washington conference agenda: Get the nasty business out of the way before next week's summit in Russia. These are the best time slots available, sir.
The extreme lack of public enthusiasm for any action - as shown by opinion polls in the US and UK - seemed barely an objection. Officials leaked information on what would be hit to an almost comic level of detail - including in a New York Times report how many missiles would likely strike a target - as though it had already all played out perfectly on their meeting-room whiteboards.
It would only be a couple of days, Bashar al-Assad was told. Damascus, line up for your medicine now.
What was forgotten were lessons that had supposedly been learned from the rush to disaster in Iraq (which was wrongly said to have chemical weapons) and the psychological scars in the public consciousness from that conflict. People and politicians alike are understandably wary of being steamrolled into another expensive foreign misadventure on false premises. They don't want facts to be made to fit the preferred narrative. If it's to be done, they want it done by the book. It's not a mood of total non-intervention: They coped with the more gradual government argument over the war in Libya.
To be fair, President Barack Obama has spoken cautiously about the complexities of the Syrian situation and the dangers of outside involvement while also blaming Assad.
But the US and Britain have generally mishandled the aftermath of the Ghouta tragedy.
They needed to initially express outrage at the apparent use of weapons of mass destruction and their general determination to respond, then compiled intelligence and waited for the UN inspectors' report.
And instead of immediately saying they could act without going through the UN and that there was "no doubt" the regime was to blame - without for days backing it up - they should have gradually explained what evidence was available and pushed again through UN diplomacy. Make the case. Let the Russians and Chinese explain why a large-scale WMD attack that killed many children does not require a response.
The British Parliament yesterday responded to the sledgehammer blows by digging in and demanding a delay to wait for the UN report. It's a stunning reminder for the political masters to always do it properly or repent afterwards.
As historian and conservative commentator Tim Stanley said yesterday: "Nobody is saying do nothing. They're saying stop, think and do the right thing". But, effectively, the badly wounded Prime Minister David Cameron is unlikely to risk another vote next week.
Liberal Guardian commentator Sunny Hundal wrote: "Cameron lost because he wanted to rush into Syria and dismissed any caution or calls for proper evidence. He misjudged the mood on both sides of the House and assumed that no one would defy him on a vote of war. He lost."
Intelligence officials in an AP report on Thursday night suggested there were holes and questions to what's known including whether Assad is in control of all his chemical weapons stocks.
The British intelligence assessment asserted (though without providing detail) that: "the Syrian regime used lethal CW on 14 occasions from 2012" and that only the Government was capable of an attack on that scale.
If that is correct, and the US decides not to act, then the sins over Iraq could end up costing the Syrian people. In other words, because the West once went to war with a Middle Eastern dictator on the basis of a lie over WMDs that weren't there, it may fail to deal properly with another who is probably using WMDs now.
Doing nothing over two years has resulted in 100,000 deaths and two million refugees having to be hosted by neighbouring countries. Doing nothing will mean more civilian deaths, refugees and destabilisation.
The argument for military action is it's the best way of sending Assad a message not to use chemical weapons again and to try to force him into negotiations. Assad has no reason to talk - he has been making advances on the ground and he has the military, diplomatic and financial backing of Russia, Iran and Hizbollah. Diplomacy has been frustrated via a divide between the major powers.
Military action would allow Obama to fulfil his "red line" vow and US credibility is important to the superpower, especially in its dealings with Syria's neighbour Iran. Backing off now could mean a worse confrontation down the track with an emboldened Tehran which could draw in Israel.
A cynical equation would suggest that military action gives the West the chance to weaken Assad by attacking his airpower, other military resources and airfields, tilting the balance in the rebels' favour, just as they are receiving Saudi-financed weapons. The US would hope that the rebels it backs among the opposition could take over.
But al-Qaeda-linked Islamist groups among the rebels are by various accounts the most organised and deadly fighters - and the most likely to take advantage of regime weakness. Air strikes are unlikely to be totally accurate or effective - civilians could be killed, chemical weapons could be hit, retaliatory strikes could target neighbouring countries. Incidents could occur that lead to more military involvement by the reluctant US.
In the end, no one can be sure of the best option in how to deal with Syria because of the strong likelihood of unintended consequences.