Three cargo ships in the Strait of Hormuz were damaged by what the United Kingdom Maritime Trade Operations called unspecified “projectiles,” jeopardizing President Donald Trump’s goal of preserving the shipping lane’s safety.

The strait was de facto closed the morning hostilities began on Feb. 28, with announcements declaring the waterway’s closure from Islamic Revolutionary Guard Corps commanders shortly after. Ships began cautiously navigating the strait over the past few days as Iran’s military capabilities have been degraded further. Iran apparently began firing on these ships on Wednesday, hitting and damaging three cargo ships in the Strait of Hormuz.