American forces have started patrolling the Turkey-Syria border to prevent further clashes between Turkish troops and Kurdish fighters, which could undermine the fight against Islamic State, U.S. officials said Friday.

The patrols are part of a far-reaching American effort to prevent the rival forces from targeting each other as the U.S. prepares to launch a major effort to drive Islamic State from its largest Syrian stronghold.

“U.S. forces are patrolling in Northern Syria to maintain stability in the area and prevent incidents that could divert efforts to defeat ISIS in Syria,” said Col. John Dorrian, a spokesman for the U.S.-led military coalition against Islamic State, also known as ISIS. […]