Somalia ? A U.S. destroyer off the coast of Somalia closed in Saturday on a hijacked Ukrainian ship loaded with tanks and ammunition, watching it to ensure the pirates who seized it do not try to remove any cargo or crew.

As Russian and American ships pursued the hijackers of the Ukrainian-operated vessel, pirates seized another ship off Somalia’s coast, an international anti-piracy group said.

The Greek tanker with a crew of 19 is carrying refined petroleum from Europe to the Middle East. It was ambushed Friday in the Gulf of Aden, said Noel Choong, who heads the International Maritime Bureau’s piracy reporting center based in Malaysia. He said pirates chased and fired at the ship before boarding it.