Britain's government weighed the possibility of military action against Syria on Thursday but faced growing scepticism from opposition leaders and deeper divisions in a country still haunted by its role in the US-led invasion of Iraq.
What seems to be delaying that decision is the fear a strike could spark a much bigger war than anyone wants.
Opposition Labour leader Jeremy Corbyn said it is "vital that parliament has the chance to debate and decide in advance" of any military action, which he warned "risks a risky escalation of the conflict".
Labour leader Jeremy Corbyn raised the spectre of the war on Thursday as he insisted MPs should be recalled from their Easter break to have their say on Syria.
The Secretary of Defence Jim Mattis has made it clear he has significant concerns over the unforeseen consequences of a strike on Syria.
"Six in ten Brits (61%) say that it should be necessary for Parliament to vote first on whether the United Kingdom takes part in military action in Syria - 18% say it should not be necessary for Parliament to vote on the matter", the pollster wrote on Twitter on the results of its survey.
President Donald Trump said Thursday that an attack on Syria could take place "very soon or not so soon at all", arguing he had never signaled the timing of retaliation for a suspected chemical weapons attack that he had suggested was imminent a day earlier.
Trump posted a tweet on Wednesday warning Russian Federation to "get ready" because missiles "will be coming" to Syria.
The attack in Douma happened late on Saturday amid a resumed offensive by Syrian government forces after the collapse of a truce with the Army of Islam rebel group.
Defence Secretary Jim Mattis warned such an attack carried the risk of spinning out of control, suggesting caution ahead of a decision on how to respond to an attack against civilians last weekend that US officials are increasingly certain involved the use of banned chemical weapons. Asked if France is planning to participate in retaliatory attacks on Syria, he was noncommittal. The White House said he would consult further with allies. In another tweet on Thursday, Trump wrote that an attack on Syria "could be very soon or not so soon at all!"
The drumbeat of military action appeared to grow louder, as Russian Federation stonewalled diplomatic efforts at the United Nations and France declared "proof" that Moscow's Syrian ally carried out a deadly chemical weapons attack that killed more than 40 Syrians.
Some MPs have backed Britain acting against Syria, warning that the use of chemical weapons was in breach of worldwide law and could not be allowed to go unpunished.
It came nearly exactly a year after a chemical attack in the northern Syrian town of Khan Sheikhoun killed dozens of people.
The Syrian government denies responsibility.
The NBC News reports come several hours after French president Emmanuel Macron said he too has "proof" that the attack used chemical weapons.
Echoing the USA stance, France's Ambassador Francois Delattre said Assad's government had reached a "point of no return" with repeated use of chemical weapons.