Japan ordered on Friday two naval vessels to join international patrols aimed at curbing pirate attacks off Somalia, after months of deliberations on how to help protect cargo ships without breaching its pacifist constitution.
The destroyers are to set off from the port of Kure in southern Japan on Saturday, three months after neighbouring China sent its own ships to the Gulf of Aden in a display of its growing military muscle.
Naval patrols from 18 countries have helped bring down the number of attacks on cargo ships from a peak of 37 in November to just seven in February.
"Piracy is a threat to the international community, including Japan, and it is an issue that should be dealt with immediately," Defence Minister Yasukazu Hamada told reporters on Friday after issuing the order.
"It is the government's important responsibility to protect the lives and property of the Japanese in the waters, which is an essential marine traffic area for our country."
The cabinet approved a new bill for submission to parliament that would broaden the legal scope for such missions.
If passed, it would allow Japan's navy to protect ships that have no connection with Japan, and also allow sailors to use weapons in a broader range of circumstances, Japanese media say.
Piracy in the Gulf of Aden, one of the world's busiest shipping areas, has become a major problem over the past six months, pushing up marine insurance premiums and forcing some ships to avoid the area.