Japan spent billions of dollars in support of the Gulf war but sent no troops or supplies, which caused resentment in some of the West's military establishments. Calls for Japan to "punch in its weight class" were met by subsequent decisions by Tokyo to send peacekeepers to Cambodia and to increase aid to the developing world.
Japan's main stake in the current Gulf crisis is oil. More than any other major power, Japan's economy is dependent on Gulf oil as a lifeline. The Japanese traditionally keep a low profile in such disputes but can generally be counted on at the United Nations to vote with the United States.
Japan involvement in Gulf War 91:
The Japanese government has pledged about $13,000 million to the overall gulf effort, including a $9,000 million pledge to Operation Desert Storm in January 1991. The Diet approved the pledge on March 1, and the U.S. government received the first contribution of $5,800 million in late March. Japan made an additional disbursement of more than $2,000 million to the United States on April 2.
Japan pledged $2,100 million in highly concessional and untied commodity loans and other forms of economic assistance to the front-line states. Japan has disbursed $60 million in refugee relief for the affected region in the Middle East, including Japanese government charters of Japanese civilian aircraft to evacuate refugees from the region and return them to their home countries.
Japan's Foreign Affairs Ministry