Japan started pulling out its troops from Iraq, sending the first group of withdrawn soldiers to neighboring Kuwait, Japanese media reported.
At least 30 Japanese troops arrived at a Kuwaiti airport on Friday afternoon, according to the Kyodo News agency.
The Japanese Defense Ministry refused to confirm the reports, citing security concerns.
There are about 600 Japanese forces based in the southern Iraqi city of Samawa on a post-war reconstruction mission.
The soldiers are banned by Japan's U.S.-imposed pacifist constitution of 1947 from firing their weapons except in self-defense.
Japanese officials said the pullout will be carried out over the next two weeks.
On June 25, the Japanese forces started the withdrawal process by sending military trucks carrying military cars, bulldozers and equipment to Kuwait.
The Japanese military presence in Iraq is unpopular at home, although no soldiers have been killed or wounded in the war-torn country.
Correspondents say the Japanese withdrawal would deal a blow to the U.S. President George W. Bush, who is facing mounting pressure at home and abroad over America's presence in Iraq and his handling of the war.
- Nine killed in Baghdad gun battle
Mahdi Army fighters, loyal to Shia cleric Moqtada Sadr, engaged in a fierce gun battle with American and Iraqi forces in Baghdad's Sadr City on Thursday, witnesses said, according to BBC.
The clashes, which lasted for four hours, killed more than nine people and wounded 30 others. There were no U.S. or Iraqi casualties.
An official in Sadr's office said that U.S. and Iraqi soldiers were backed by tanks, armored vehicles and aircraft.
The U.S. army claimed that its operation in Sadr City was aimed at arresting an "insurgent leader".
But a top official in Moqtada Sadr's office said the intended target of the operation was Abu Dera, a Shia Imam and a top official in the Mahdi Army.
"We strongly condemn the attacks of U.S. and Iraqi forces, and we call on the Iraqi government to protect its citizens against these kinds of attacks," Sahib al-Amiri, an official in Sadr's movement, told AFP.
The Mahdi Army has regularly fought U.S. occupation forces since the 2003 invasion.