The UN International Maritime Organization (IMO) paused its program to shepherd ships and seafarers through the Strait of Hormuz on Thursday after a cargo ship reported a suspected attack, reigniting fears over a preliminary deal to end the Iran war.

While the waterway had effectively been blocked since the war began on February 28, maritime traffic has increased over the past week amid peace talks.

A U.S. official told The Associated Press that the vessel was hit by an Iranian drone.