BEIRUT • An Islamic State suicide bomber targeted a joint convoy of U.S. and allied Kurdish forces in northern Syria on Monday, marking the second attack against U.S. troops in less than a week and further highlighting the dangers surrounding U.S. plans to withdraw forces after a declaration that the extremist group had been defeated.

The attack happened on a checkpoint on the edge of the town of Shaddadeh in the Hassakeh province, on a road used by local Kurdish fighters and the U.S.-led coalition fighting IS militants near the Iraqi border.

U.S. military Col. Sean Ryan said there were no casualties among the U.S.-led coalition members. “We can confirm a combined U.S. and Syrian partner force convoy was involved” in the suicide bomb attack, he said.

“We will continue to review the situation and provide updates as appropriate,” he added.

Monday’s bombing came days after a suicide attack killed 19 people, including two U.S. service members and two American civilians, in the northern Syrian town of Manbij. That bombing, outside a popular restaurant frequented by American troops, was the deadliest assault on U.S. troops in Syria since American forces moved into the country in 2015. The extremist group claimed both attacks in statements carried by its Aamaq news agency. IS has been driven from virtually all the territory it once held in Syria and Iraq.