In an interview en route to a US Air Force base in southern Japan, Rumsfeld was asked about the plan to restore Iraq's sovereignty by June.

"The time table or the way ahead that the (Iraqi) Governing Council has been describing relates to the governance aspects of the country and not to the security aspects," he said. "That's on a separate track."

Rumsfeld said the United States continues to plan to rotate a new contingent of troops into Iraq next year, with no final pullout date set yet. Accelerating the political process will not affect military planning, he said.

"This has nothing to do with US troops and coalition troops in Iraq," he said.

The plan, endorsed by the Iraqi Governing Council Saturday, reflects Washington's desire to speed up the hand over of power as attacks against American occupation forces grow more sophisticated and deadly. It came as the US death toll since the war began passed the 400 mark.

Rumsfeld was to meet later Sunday with Governor Keiichi Inamine of Okinawa, the southern island where a majority of the 47,000 Japan-based US troops are stationed. He was also scheduled for a visit with US troops, including Marines at Camp Foster, home of the 3rd Marine Division.

While the United States counts Japan among its strongest and most reliable allies, the presence of thousands of American troops on Japanese soil often in urban areas whose residents are disturbed by the noise is a source of friction.

Central to those tensions is the question of whether to extend fuller legal protections to US service members accused of crimes.

At a joint news conference with Ishiba, head of Japan's Defence Agency, Rumsfeld also thanked the government for the billions of dollars in humanitarian aid it has pledged for Iraq's reconstruction. He gave no hint of disappointment at Japan's delay in sending security troops to Iraq.

Ishiba said the government is closely monitoring the situation in Iraq and is inclined to send troops.

"We would like to do it as soon as possible," he said.

A military fact-finding team left Tokyo for Iraq on Saturday to determine where and when it might be safe to send Japanese troops to help with reconstruction and other non-combat duties.

The mission came two days after Japanese government said it would delay long-discussed plans to send peacekeepers because of deteriorating security following a deadly suicide bombing in southern Iraq. Japanese media reported the mission had been hastily organised in a show of solidarity with Rumsfeld.