Three Japanese warships will set sail Friday on a reconnaissance mission after the government approved a role in the war on terrorism for Japan's military.

The flotilla — two destroyers and a supply vessel — will head for the Indian Ocean to gather information for planners who are finalizing a blueprint for Japan's contribution to the U.S.-led campaign.

Under a new law authorizing its armed forces to provide logistical and other non-combat support, Japan's navy is expected to transport supplies and fuel for coalition forces.

Japan's constitution restricts its military to defensive missions, and the naval vessels will be the first deployed overseas during hostilities since World War II. Ten years ago, Japan agreed to send minesweepers to the Persian Gulf only after the fighting there was over.

"This mission is a first, but we are trained to be able to respond to whatever contingencies may arise," said Rear Admiral Hirotaka Honda, the flotilla's commander. "We want to show what we are capable of."

With a total of 700 sailors aboard, the destroyers Kurama and Kirisame and the fleet support ship Hamana are to leave their base at Sasebo, 615 miles southwest of Tokyo, and steam through the Strait of Malacca into the Indian Ocean, officials said.

The warships will reach the Indian Ocean in about one week, Honda said. They are to spend a couple of months scouting possible routes for other Japanese vessels to ferry supplies to American-led forces.

Japan had also reportedly planned to dispatch a destroyer equipped with a high-tech Aegis combat radar system, but decided against it amid concern that deploying the ship would weaken the country's ability to defend itself.

Analysts have suggested the government backed away from deploying its most advanced class of warship to avoid antagonizing its political opponents and other Asian countries, but Honda steered away from the controversy.

"Our job is to do the best we can with the equipment we are given," he said in response to a reporter's question.

Prime Minister Junichiro Koizumi, whose Cabinet approved the mission Thursday, is determined to make a conspicuous contribution to the war against terrorism — and avoid the "checkbook diplomacy" for which Japan was criticized during the Gulf War a decade ago.

But the prime minister must strike a balance between U.S. expectations of support and concerns in the rest if Asia about the loosening of restraints on Japan's armed forces.

Asian countries have bitter memories of atrocities committed by Japanese troops in their rampage through the region in the first half of the century and react sharply to any sign that Japan is expanding its military role.

Japan's constitution — written by the U.S. occupation authorities after World War II — bans the nation from using force to settle international disputes.