Donald Trump has warned Russia, Syria and Iran will be making a “grave humanitarian mistake” if they go ahead with an assault on Idlib, the last opposition stronghold in the country.
President Bashar al-Assad and his allies have been amassing a huge military presence near to rebel-held Idlib, where opposition fighters and Islamist groups are holding out among a population of around 3 million people.
Mr Trump tweeted on Monday night that Syria’s President Bashar al-Assad “must not recklessly attack Idlib Province”.
He added: “The Russians and Iranians would be making a grave humanitarian mistake to take part in this potential human tragedy.”
The UN said last week it was bracing for “the most horrific tragedy” in Idlib and dubbed it a “dumping ground” for fighters and civilians who have been pushed out of successive pockets of opposition-held territory.
Staffan de Mistura, the UN envoy for Syria, warned as many as 800,000 people could be displaced if the fighting does begin.
In his tweet, the US president went one step further, suggesting “hundreds of thousands of people could be killed”. That might seem unlikely, given an estimated death toll of between 400,000 and half a million for the entire seven-year duration of the Syrian civil war.
Nonetheless, Syria and its allies have been ramping up the aggressive rhetoric towards Idlib. Mr Trump’s tweet came as Iran's foreign minister Mohammad Javad Zarif said at the start of a visit to Damascus that "terrorists must be purged” from the province and the entire of Idlib returned to government control.
"Syria's territorial integrity should be safeguarded and all tribes and groups, as one society, should start the reconstruction process, and the refugees should return to their homes," Mr Zarif said.
He met with Mr Assad and his foreign minister Walid al-Moallem, who is just back from a visit to Moscow.
The visit comes days before the leaders of Iran, Turkey, and Russia are expected to meet in Iran to discuss the situation in Idlib.
During their meeting, Mr Assad and Mr Zarif discussed the agenda of the summit in Iran.
A statement from Mr Assad's office said Iran and Syria "had similar views on the different issues" to be discussed. It provided no further details.
Mr Zarif said it was necessary to consult "with our Syrian friends" ahead of the 7 September summit, according to the Fars news agency.
Iran has lent crucial military and economic support to Mr Assad throughout the civil war and the discussions are expected to focus on the decisive battle for Idlib.
Mr Assad has vowed to defeat the opposition in its last refuge in the north-western province if the rebels do not surrender to government rule.
Nearly half of the people currently living in Idlib have already been displaced more than once by the civil war.
Tens of thousands fled there after surrendering, choosing to relocate to an opposition-held area rather than risk reprisals or forced conscription at the hands of the government.
In their meeting on Monday, Mr Assad and Mr Zarif also discussed what they called "western pressure" on their two countries, in apparent reference to the US sanctions on Iran and calls for limiting Iran's role in Syria.
Israel has grown nervous of Iran's growing presence in Syria and threatened to prevent a build-up of pro-Iranian forces near its frontiers with Syria.
Russia, another Syria ally, and Damascus have also said that Western countries are preparing to carry out strikes against Syria ahead of the Idlib offensive. They claim such threats were part of the West's attempt to undermine Syria's drive to restore control over all its territories.
The US and France have warned an Idlib offensive would trigger a humanitarian crisis and that a chemical attack in Idlib would prompt a western retaliation.
In the statement from the Syrian president's office, Mr Assad and Mr Zarif said that resorting to "threats and pressure reflect the failure of those countries to realise their plans for the region after Syria and Iran confronted them".
Additional reporting by AP
