As the first Japanese soldiers headed into Iraq Monday, Japan's prime minister defended his order for the dispatch. Prime Minister Junichiro Koizumi says Japan must send a full deployment of troops to Iraq because "peace cannot be achieved only with words."

Mr. Koizumi made the remark in a nationally televised policy speech opening a new parliamentary session.

The prime minister says for Japan to be a responsible member of the international community, it cannot leave the humanitarian work to others and only make a financial contribution.

As the prime minister delivered his speech, an advance team of Japan's army was on its way into Iraq from Kuwait in a convoy of armored vehicles. It is the first time since the Second World War that Japanese troops have entered a country where hostilities are underway.

Japan's parliament has yet to formally approve the full dispatch of hundreds of Japanese troops, which will provide drinking water and rebuild schools in the southern Iraqi city of Samawah.

Opposition politicians plan to grill Mr. Koizumi about his decision to send the troops - a move supported by less than half the public.

Japan's Defense Agency says it plans to deploy a total of six-hundred ground troops to Iraq by late March, and an additional four hundred air and naval personnel providing support in the region.

Also speaking in parliament on Monday, Foreign Minister Yoriko Kawaguchi says the troop dispatch is in Japan's national interest. The country depends on Middle East oil for about 90 percent of its petroleum supply.

Ms. Kawaguchi told lawmakers if Iraq turns into a failed state, it would become a base for terrorism and pose a threat to the Middle East and the entire international community. She added that Japan must not give in to terrorism.

The Foreign Minister also announced that Japan would increase its aid to Iraq. The country has already pledged a total of five billion dollars worth of assistance, including one-and-a-half billion dollars in grant aid.