He also said chances the Syrian insurgents were behind the attack were "vanishingly small," adding: "We do believe this is a chemical attack by the Assad regime on a large scale."
Deja vu all over again.
Listening to Hague, Tony Blair's assertion to Parliament that Iraq could unleash weapons of mass destruction "in 45 minutes" came to mind - as did the nonsense from British "intelligence" of September 9 2002 that "Iraq has probably dispersed … weapons, including its CBW weapons.
"Intelligence also indicates that chemical and biological munitions could be with military units and ready for firing within 20-45 minutes."
Just over two weeks earlier, on August 26, then US vice-president Dick Cheney said: "Simply stated, there is no doubt that Saddam Hussein now has weapons of mass destruction."
Then on September 12 2002 president George W Bush added: "Right now, Iraq is expanding and improving facilities that were used for the production of biological weapons."
Such lies are a litany.
On August 20 President Barack Obama asked the US Department of Justice to grant Bush, Cheney, Donald Rumsfeld, Colin Powell, Condoleezza Rice and Paul Wolfowitz procedural immunity in a case alleging that they planned and waged the Iraq war in violation of international law.
No doubt Britain will faithfully follow in their master's footsteps and demand the same for Tony Blair and his co-conspirators.
But William Hague and David Cameron should remember that you can run, but you can't hide. Immunity in the US and Britain does not apply globally and, if Syria becomes the current government's Iraq, like another alleged war criminal Henry Kissinger they will spend the rest of their lives calling their lawyers before travelling, should they be arrested upon landing.