Washington and Moscow trade chemical attack warnings as Russian naval buildup grows ahead of strike on Syria’s Idlib.

Russia has deployed a dozen warships to the Mediterranean Sea in what a Russian newspaper on Tuesday called Moscow’s largest naval buildup since it entered the Syrian conflict in 2015.

The reinforcement comes as Russia’s ally, Syrian President Bashar al-Assad, is believed to be considering a major assault on the last rebel-held enclave in northern Idlib province.

Russia has accused the United States of building up its own forces in the Middle East in preparation for a possible strike on Syrian government forces.

On Saturday, the Admiral Grigorovich and Admiral Essen frigates sailed through Turkey’s Bosphorus towards the Mediterranean, Reuters news agency images showed.

The day before, the Pytlivy frigate and landing ship Nikolai Filchenkov were pictured sailing through the Turkish straits that connect the Black Sea with the Mediterranean. The Vishny Volochek missile corvette passed through earlier this month.

The Izvestia newspaper said Russia had gathered its largest naval presence in the Mediterranean since it intervened in Syria in 2015 and turned the war‘s tide in Assad’s favour.

The force included 10 vessels, most of them armed with long-range Kalibr cruise missiles, Izvestia wrote, adding more ships were on the way. Two submarines had also been deployed.

The Syrian government is gearing up for an expected offensive in Idlib province, which is home to nearly three million people and has a large al-Qaeda presence in addition to several Syrian rebel groups.

It borders Turkey, which fears an offensive may trigger a humanitarian and security catastrophe.

Chemical attack?

The US on Tuesday warned the Russian and Syrian governments against chemical weapon use in Syria.

State Department spokeswoman Heather Nauert said the US “will respond to any verified chemical weapons use in Idlib or elsewhere in Syria … in a swift and appropriate manner”.

The comments came as Russia again accused Syrian rebels of preparing a chemical attack that Moscow said will be used to justify a Western strike against Syrian troops.

Russia’s Deputy Foreign Minister Sergei Ryabkov said on Tuesday an al-Qaeda-linked group is preparing the attack in Idlib.

Western countries and independent analysts say Syrian government forces have conducted several chemical weapons attacks over the course of the seven-year civil war. Alleged chemical attacks in 2017 and earlier this year led the US to launch punitive strikes against Syrian forces.

The Syrian government denies ever using chemical weapons.

Damascus has been sending reinforcements towards Idlib for weeks in advance of an expected attack against the last major rebel stronghold in the country.

‘Russian propaganda’

Last week, Russian Major-General Alexei Tsygankov, who heads the centre for reconciliation of warring parties in Syria, claimed British special services were involved in plans for the alleged provocation.

That brought a heated denial from Britain’s United Nations Ambassador, Karen Pierce, during a Security Council session on the humanitarian situation in Syria held on Tuesday.

“Even by the egregious standards of Russian propaganda, this is an extraordinary allegation,” she said. “It is wholly untrue.”

She said the claim was either aimed at increasing “the amount of fake news in the system [or] as a smokescreen for a possible impending attack by the Syrian regime, once again against its own people, in Idlib”.

Russia’s UN Ambassador Vassily Nebenzia said: “If the defence ministry says something, then it says that based on concrete facts”.

“The Syrian armed forces do not have chemical weapons and have no plans to use them. There is no military need for that. We have stated that more than once. People in their right minds will not use means that are useless from a military point of view in order to trigger reprisals by three major powers,” said Nebenzia.

The UN director of humanitarian operations warned a major offensive in Idlib “has the potential to create a humanitarian emergency at a scale not yet seen” in the seven-year civil war.

John Ging called on members of the UN Security Council on Tuesday “to do all they can to ensure that we avoid this”.