U.S. President Donald Trump on Monday warned Syrian President Bashar Assad and his allies Iran and Russia not to "recklessly attack" Syria's rebel-held Idlib province, warning that hundreds of thousands of people could be killed if they did.
"The Russians and Iranians would be making a grave humanitarian mistake to take part in this potential human tragedy," Trump tweeted Monday. "Hundreds of thousands of people could be killed. Don't let that happen!"
Assad is reportedly preparing a phased offensive to regain Idlib.
The northern province and surrounding areas are the last major enclave held by insurgents fighting Assad, who has been backed by both Russian and Iranian forces in Syria's seven-year civil war. They area in question is home to some three million civilians.
Trump has sought better relations with Russia since taking office in 2017, but the U.S. has been unable to rein in Moscow's military and diplomatic support for Assad.
U.S. Secretary of State Mike Pompeo on Friday said Washington views any government assault on Idlib as an escalation of Syria's war, and the State Department warned that Washington would respond to any chemical attack by Damascus.
U.S. Ambassador to the United Nations Nikki Haley tweeted late Monday "All eyes on the actions of Assad, Russia, and Iran in Idlib. #NoChemicalWeapons"
Earlier Monday, Iran's foreign minister said at the start of a visit to Damascus that "terrorists must be purged" from Idlib and the entire northwestern province returned to government control.
Mohammad Javad Zarif's comments were reported by Iran's semi-official Fars news agency and came as Syrian forces and their allies were preparing for an assault.
"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," Zarif said.
Assad's office said in a statement that "the two sides asserted that the pressures from some Western states on Syria and Tehran will not deter the two countries from continuing to defend their principles."
In Damascus, Zarif met with Assad, Syrian Prime Minister Imad Khamis and Foreign Minister Walid Muallem, who asked that Iran continue its support for government forces. The visit comes just days before the leaders of Iran, Turkey, and Russia are expected to meet in Iran to discuss Idlib.
During their meeting, Assad and Zarif discussed the agenda of the summit in Iran. A statement from Assad's office said Iran and Syria "had similar views on the different issues" to be discussed. It provided no further details.
Zarif said it was necessary to consult "with our Syrian friends" ahead of the Sept. 7 summit, according to Fars.
Iran has lent crucial military and economic support to Assad throughout the ongoing war, and the discussions are expected to focus on the decisive battle for Idlib.
Turkey, which has long supported anti-Assad rebels, has cooperated with Russia and Iran on talks over Syria in recent years and has troops in the Idlib region on an observation mission.
Last week, Iran's defense minister traveled to Damascus and signed an agreement for defense cooperation between the two countries with his Syrian counterpart.
Iranian Foreign Ministry spokesman Bahram Qassemi said Iran would continue its support for Syrian government forces in its battle in Idlib.
Assad has vowed to defeat the opposition in its last refuge in the northwestern province if the rebels do not surrender to government rule.
Tens of thousands of people fled to Idlib after surrendering in government offensives elsewhere, choosing to relocate to an opposition-held area rather than risk reprisals or forced conscription at the hands of the government.
U.N. officials believe an offensive on Idlib would trigger a wave of displacement that could uproot an estimated 800,000 people and discourage refugees from returning home.
Thousands of government troops and allied fighters have been massing in areas surrounding the province.
In their Monday meeting, Assad and Zarif also discussed what they called "western pressure" on their two countries, in an apparent reference to U.S. sanctions on Iran and calls for limiting Iran's role in Syria. Israel has grown nervous of Iran's growing presence in Syria and has threatened to prevent a build-up of pro-Iranian forces near its frontiers with Syria.
France has also warned that an Idlib offensive would trigger a humanitarian crisis and that a chemical attack in Idlib would prompt a western retaliation.
