Assad 'has been warned' on Idlib chemical use: Mattis

US Defense Secretary Jim Mattis stressed on 11 September that Syrian President Bashar al-Assad has been well warned against any chemical weapons use in an anticipated assault on Idlib province.

The Assad regime has twice been targeted by US air and missile strikes after previous alleged chemical attacks, and US officials have in recent days said additional action would follow if Assad were to use the banned weapons in rebel-held Idlib.

Mattis told Pentagon reporters: ‘In Idlib, we're watching very closely what the Assad regime, aided and abetted by the Iranians and the Russians are up to there.’

Pointing to a US missile strike on a Syrian air base in April 2017 after Assad's jets launched an alleged chemical attack in Idlib, Mattis noted that the Syrian leader suffered massive losses to his air force.

Mattis, referring to the unusual nose cones on Russian-built jets, said: ‘The first time around, he lost 17% of his pointy-nosed air force airplanes. He's been warned, and so we'll see if he's wised up.’

A second strike, in April 2018, saw British and French militaries assist the US-led mission.

Idlib province and adjacent rural areas form the largest piece of territory still held by Syria's beleaguered rebels, worn down by a succession of government victories in recent months.

Assad has now set his sights on Idlib, and his forces have stepped up bombardment of the densely populated province since the beginning of the month.