Vice President Mike Pence said that he would soon be leading a delegation to Turkey and that President Trump spoke with Turkish President Recep Tayyip Erdoğan and called for an “immediate end” to Turkey’s invasion of Syria.

Speaking outside the White House on Monday after the U.S. announced new tariffs and sanctions against Turkey, Pence said that Erdoğan initiated a phone call with Trump over the ongoing unrest in northern Syria. Pence said that Trump was firm in his calls for a ceasefire to be worked out.

“President Erdoğan reached out and requested the call, and President Trump communicated to him very clearly that the United States of America wants Turkey to stop the invasion, to implement an immediate ceasefire, and to begin to negotiate with Kurdish forces in Syria to bring an end to the violence,” Pence said.

During the call, Pence said Trump told the Turkish president the U.S. would help mediate and arbitrate an agreement between forces in Syria and Turkish military. Pence said that Trump has directed him and national security adviser Robert O’Brien to travel to Turkey in order to work toward arbitrating an end to the violence.

Pence also said that Erdoğan gave Trump a “firm commitment” that Turkey would not launch an offensive against the Kurdish-controlled city of Kobanî.

The vice president said that Trump met with Republican Sen. Lindsey Graham on Monday about Syria and noted that Graham was also present when Trump signed the sanctions, which in addition to other economic punishments, raise tariffs on Turkish steel from 25% to 50%.

The move comes a day after the Syrian Democratic Forces, a majority Kurdish group based in northeast Syria, reportedly struck a deal with Syrian leader Bashar Assad. The Kurds agreed to allow forces loyal to Assad to fill the vacuum left after the U.S. departure in order to protect against Turkish attacks.

Hundreds of people associated with the Islamic State reportedly escaped a Syrian detainment camp on Sunday, further fueling fears of an ISIS resurgence in the turbulent region.

