Shortly after Theresa May declared that she could act in Syria without approval from Parliament, the Telegraph is reporting that the prime minister has ordered UK submarines to travel within striking range of Syria, and adds that strikes could begin as early as Thursday, which is when May will call an emergency cabinet meeting over Syria.
With the US's Truman carrier still a month away, the "coalition" will rely on UK and French ships. US air support will likely also be involved, suggesting that any attack on Syria may be based on a joint UK-French naval operation, with US air support.
Meanwhile, as reported earlier, President Bashar al-Assad has already started moving aircraft and military vehicles away from air bases that could become targets for the coalition's bombs.
Mrs May hardened her stance towards Syria as she said the UK, US and France were “rapidly reaching” a clear picture of who was responsible for last Saturday’s chemical attack on Douma, Eastern Ghouta.
Mrs May said "all the indications are that the Syrian regime was responsible", adding: "The continued use of chemical weapons cannot go unchallenged."
Sources indicated to the Telegraph that Mrs May has now abandoned any intentions of seeking the backing of Parliament - which does not sit until Monday - for military action.
There are reports that President Bashar al-Assad has already started moving aircraft and vehicles away from air bases that are likely to be targeted, and both Mr Trump and President Emmanuel Macron of France have stressed the need to act swiftly.
On Wednesday afternoon, in the US, President Trump told reporters to expect a decision Wednesday night, while Press Secretary Sarah Sanders has said "a number of options" are on the table regarding US action in Syria.
Trump has also reportedly come to the conclusion that Syria was behind the brutal gas attack in rebel-held Ghouta - and that Russia failed to guarantee that Syria's government had given up its stockpile of chemical weapons.
A source inside Whitehall purportedly told the Telegraph that May has broad support to join in US airstrikes in Syria, but that "further discussions" are needed with the US and France before a final decision about an escalation could be made. Gaining the backing of her cabinet is the last obstacle for May. The Telegraph added that whatever she decides, military actions are expected to be carried out before Monday.
May has recalled her cabinet ministers from their Easter break for an emergency meeting where she will discuss how the UK should respond.