The Labour leader also said Parliament should “always be given a say” on any military action.
Speaking during a visit to Plymouth, Mr Corbyn said he had been making the case for Parliament – which is currently in recess for Easter – to be given a say on any military action for “many, many years”.
He said all countries had to get “around the table” to come up with a political solution to the war in Syria, adding: “We cannot risk an escalation any further than it’s gone already.”
Asked what it would take for him to back action this time, he said: “Listen, what happened last weekend was terrible. What we don’t want is bombardment which leads to escalation and a hot war between the US and Russia over the skies of Syria.”
The SNP also called for Parliament to have a say before any UK military action is authorised.
Defence spokesman Stewart McDonald urged the UK and its allies to “clamp down on the development and use of chemical weapons”.
He added: “Air strikes have not prevented these attacks and will not provide the long term solutions needed to end the war.”
On Wednesday, President Donald Trump threatened a major new escalation of the seven-year-old US war for regime change in Syria, declaring in a tweet, “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!’” Trump’s threat expresses the criminality of the US-led campaign against Syria. The president of the United States is about to launch an unprovoked war of aggression. The US and European governments lie without restraint to justify their predatory war aims and the most incredible statements go unchallenged by the press: here.