SINGAPORE — Two Chinese destroyers and a supply ship are on their way to join other foreign warships on anti-piracy patrols in the Gulf of Aden and waters off Somalia. This is a milestone for a navy that has long focused on coastal defense and lacked the capability to project power overseas.

It is likely to be the first of an increasing number of long-distance deployments as China takes its place among the top ranks of world navies alongside the fleets of the United States, Europe, Russia, Japan and India.

Beijing's decision to follow the other four permanent members of the United Nations Security Council (Britain, France, Russia and the U.S.) in sending warships to pirate-plagued waters off the Horn of Africa is the first time since the ruling Chinese Communist Party came to power in 1949 that the navy has been used to protect U.N. aid shipments, key maritime trade routes and Chinese vessels in foreign waters. The two Chinese missile-armed destroyers carry commandos and helicopters. They are expected to operate in the area for at least three months. Rear Admiral Xiao Xinnian, deputy chief of staff of the Chinese Navy, told journalists in Beijing that the length of the mission would depend on the U.N. mandate and conditions in the area.