In an address to parliament, Johnson told MPs that the U.K. could join the U.S. in airstrikes against the Assad regime.

“It is my belief, though I stress no such decision has yet been taken, that were such a request to be made in future, were it to be a reasonable request in pursuit of similar objectives, then I think it would be very difficult for the United Kingdom to say no,” Johnson said.

He also contended that sarin gas was used by the regime in the most recent chemical weapons attack that killed dozens of civilians, including children, in Khan Sheikun.

“We know beyond doubt that two Sukhoi-22 aircraft took off from Shayrat airfield where we know that chemical weapons are stored,” Johnson said. “We know that they were overhead at 6.39 a.m, when, according to all eyewitness accounts, the attack took place.

“We know from shell fragments in the crater that not only had sarin been used, but sarin carrying the specific chemical signature of sarin used by the Assad regime,” he said.

There was “only one conclusion — that the Assad regime almost certainly gassed its own people in breach of international law and the rules of war”, Johnson said.

Underlining an open support for U.S. strikes, Johnson claimed it helped “create an opportunity to break the deadlock“ and pave the way for a political settlement and a truce, following a succession of failed cease-fires.

“The essential thing will be to have a political process that preserves the institutions of the Syrian state while decapitating the monster,” he said.

In response to a question about revoking British citizenship for Assad’s wife, Asma, Johnson said individual files could not be discussed but he conceded she was on a U.K. government list of sanctioned individuals.

Home Secretary Amber Rudd was urged to consider revoking the British passport of UK-born Assad after her social media posts in support of her husband’s regime.

Anadolu Agency