President Donald Trump has called for Russia to end its support for the Syrian regime’s “atrocities” as he expressed US concern over violence in the Idlib region, the White House said Sunday.

In a call with Turkish President Recep Tayyip Erdogan, Trump “expressed concern over the violence in Idlib, Syria and… conveyed the United States’ desire to see an end to Russia’s support for the Assad regime’s atrocities.”

President Bashar al-Assad’s forces made new gains Sunday in their offensive against the last major rebel bastion in the northwest region of Idlib.

Backed by Russian air strikes, Syrian government forces have kept up the assault in Idlib and areas of neighbouring Aleppo and Latakia provinces since December.

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On Sunday, after clashes and air strikes, regime forces “were in control of all the villages and small towns around Aleppo for the first time since 2012,” the Syrian Observatory for Human Rights said.

The Russian-backed offensive has triggered the largest wave of displacement in Syria’s civil war, with 800,000 people fleeing since December, the United Nations says.

In the Saturday phone call with Erdogan, Trump also “reiterated that continued foreign interference in Libya would only serve to worsen the situation.”

Libya has been mired in chaos since a 2011 NATO-backed uprising killed longtime dictator Moamer Kadhafi, with two rival administrations vying for power.

States including Russia, France, the United Arab Emirates, and Egypt support strongman Khalifa Haftar, while the UN-recognised Government of National Accord is backed by Turkey and Qatar.