A British-owned cargo ship sank in the Red Sea about two weeks after being damaged in a missile attack by the Iran-backed Houthi militia, and the fertilizer it was carrying now posed an environmental risk, the United States military said late Saturday.

The assault last month on the vessel, the Rubymar, involved two antiship ballistic missiles launched from Yemen. The sinking appeared to be the first since the Houthis began targeting ships in an effort to put pressure on Israel to end its military siege in Gaza.

The U.S. military’s Central Command confirmed the Rubymar’s sinking in a statement on social media. It said the ship sank early Saturday while carrying a load of 21,000 metric tons of ammonium phosphate sulfate fertilizer that now presented “an environmental risk in the Red Sea.”

The ship also poses a “subsurface impact risk” to other ships moving through the area, a busy international shipping lane, the Central Command said.

The Rubymar was an “environmental disaster” even before sinking because the attack created an 18-mile oil slick, Central Command warned last month. It said that the disaster could worsen if the fertilizer were to spill into the sea.

No other details about the sinking, or the risks it posed to the environment or to commercial shipping, were immediately available on Sunday morning. The Rubymar sailed with a Belize flag. The ship’s operator, Blue Fleet Group, based in Greece, did not respond to an inquiry.

After the attack last month, the Rubymar’s 24 crew members were taken to Djibouti by a vessel operated by a French shipping company. Djibouti port officials said at the time that the crew members were from Syria, Egypt, India and the Philippines.