AKCAKALE, Turkey (AP) — Turkey’s president says he won’t halt its military offensive in northeast Syria, despite growing pressure and sanctions from NATO allies.

President Recep Tayyip Erdogan’s comments came as Washington, which has announced limited sanctions on Turkey, said U.S. Vice President Mike Pence will travel to Ankara Wednesday to try and reach a cease-fire deal.

Speaking to a group of journalists, Erdogan said he told President Donald Trump: “We could never declare a ceasefire,” adding that Turkey wouldn’t negotiate with “terrorists.”

Erdogan said he was “not concerned” by sanctions imposed on Turkey.

Turkey launched its offensive against Syrian Kurdish fighters it considers terrorists after Trump announced he was withdrawing U.S. troops.

Russia has signaled its role as de facto power broker in the conflict, deploying forces near the border following America’s pullout.