Turkey began violating a deal to temporarily halt its offensive into northern Syria early today, US officials told Al-Monitor as reports emerged from the ground of artillery attacks against Kurdish fighters and civilians in a city where American and Turkish forces recently held joint patrols.

By Friday afternoon, the Turkish military had advanced on Ras al-Ain, a senior US official said, one of the sites of the joint "security mechanism" in northern Syria the Pentagon established to assuage Turkey’s concerns over the Kurdish military presence.

Mustafa Bali, a spokesman for the formerly US-backed Syrian Democratic Forces (SDF), said Turkish violations of the deal, which the Kurdish-dominated group agreed to abide by, began on Thursday evening. Dave Eubank, an American aid worker in nearby Sari Kani, said “hundreds” of wounded had been trapped by the Turkish assault and a nearby hospital had taken damage from repeated shelling. 

Turkish President Recep Tayyip Erdogan called reports of new clashes "nothing but disinformation" in a press conference on Friday, but a tweet from President Donald Trump indicated that Erdogan had conceded that "minor sniper and mortar fire" did occur.