Theresa May
Theresa MayReuters

British Prime Minister Theresa May has ordered British submarines to move within missile range of Syria in readiness for strikes against the Syrian military that could begin as early as Thursday night, Reuters reported on Wednesday, citing the Daily Telegraph newspaper.

The British daily quoted government sources as saying Britain was “doing everything necessary” to be able to fire Tomahawk cruise missiles from submarines against military targets in Syria.

A separate report in Sky News said May will convene a special "war cabinet" on Thursday which is expected to be asked to approve a form of British participation in action led by France and the U.S. aimed at Syrian President Bashar Al-Assad's chemical weapons infrastructure.

Meanwhile, White House press secretary Sarah Huckabee Sanders told reporters no decision has been made yet on Syria.

She added reporters that "the president holds Syria and Russia responsible for this chemical weapons attack."

"It sounds like all options are on the table and a final decision hasn't been made," Sanders said, adding the president "has not laid out a timetable.

Earlier on Wednesday, Trump mocked the Russian government's threat to shoot down any U.S. missile launched at Assad’s forces.

"Russia vows to shoot down any and all missiles fired at Syria. Get ready Russia, because they will be coming, nice and new and ‘smart!’ You shouldn’t be partners with a Gas Killing Animal who kills his people and enjoys it!" he tweeted.

"Our relationship with Russia is worse now than it has ever been, and that includes the Cold War. There is no reason for this. Russia needs us to help with their economy, something that would be very easy to do, and we need all nations to work together. Stop the arms race?" added Trump.

Tensions have run high since over 150 people were killed in an alleged chemical weapons attack in the city of Douma, east of Damascus, on Saturday night.

A day later, Trump castigated the Syrian government and Assad, calling the apparent chemical weapon attack “sick”, and warning that the “Animal Assad” would have a “big price to pay” for the use of sarin nerve gas.

Trump, who had previously spoken of pulling U.S. forces out of Syria, later said he was weighing his response to the latest atrocity committed by the Assad regime.