Turkish President Recep Tayyip Erdogan says threats of sanctions and arms embargoes by Western powers will not halt his country’s cross-border military offensive against Kurdish militants in Syria’s northeast.

The U.S. is withdrawing all remaining troops from northern Syria, as President Donald Trump said Sunday it was “very smart… for a change” to not be involved in the fighting sparked by Turkey’s onslaught against the U.S.’s long-time battlefield ally, Kurdish fighters.

Tuesday night, two small Islamic State sleeper cells inside Syria’s Raqqa governorate, which is held by the largely Kurdish Syrian Democratic Forces (SDF), targeted two separate SDF positions in region.