A Singapore-flagged container ship and an Antigua and Barbuda-flagged bulk carrier have sunk near the Strait of Hormuz following separate projectile attacks, adding to growing threats against commercial shipping in a waterway critical to global energy supplies.

The vessels, identified as the GFS Pride and Cape Dao, were reported sunk Wednesday by maritime security sources. The incidents mark the latest losses in a series of attacks on commercial vessels since the U.S.-Iran war began on Feb. 28.

The GFS Pride sustained damage and caught fire while transiting the Strait of Hormuz on Tuesday before sinking, according to Singapore’s Maritime and Port Authority. All 21 crew members were safely evacuated, and no injuries were reported.

The Singapore-flagged container ship had a capacity of 2,824 twenty-foot equivalent units. Its United Arab Emirates-based manager, GFS Ship Management FZE, was not immediately available for comment.

Singapore’s maritime authority condemned the attacks, calling them “unprovoked, unjustifiable, and a breach of international law.” The agency also expressed deep concern over continued threats to commercial shipping in the strait.

The second vessel, the Cape Dao, an Antigua and Barbuda-flagged dry bulk carrier, was struck by a projectile on Sept. 23. British maritime risk management firm Vanguard said Wednesday that the ship was reported to be sinking after an unsuccessful rescue attempt. Its UAE-based manager, Peonies Shipmanagement FZE, could not immediately be reached for comment.

The sinkings come amid escalating tensions around the Strait of Hormuz, a strategic waterway through which roughly one-fifth of global oil and liquefied natural gas trade passed before the conflict began.

Iran has sought to restrict maritime traffic through the strait following U.S. and Israeli strikes on Feb. 28, using control over the waterway as leverage against Washington. The United States has responded with a naval blockade of Iranian ports and expanded sanctions targeting Tehran.

Two senior Iranian officials told Reuters that Iran has increasingly employed new tactics against vessels in the strait as it seeks to keep oil prices elevated and influence U.S. midterm elections. Although attacks have largely focused on tankers, cargo and container ships have also been targeted, disabled or sunk.

The GFS Pride is the second vessel reported sunk since the war began, according to data from the International Maritime Organization, the United Nations agency responsible for shipping. In March, the Maltese-flagged container ship Safeen Prestige was struck by a projectile and later sank north of the strait. In April, Iran’s Islamic Revolutionary Guard Corps attacked and seized the container ship MSC Francesca.