The United States has asked Japan for contributions in the event of war with Iraq, as Washington steps up international pressure to force Baghdad to abandon its weapons of mass destruction, U.S. sources said Thursday.

The request, conveyed by a senior official of the U.S. Embassy in Tokyo to a senior Foreign Ministry official, did not mention any specific military assistance, the sources said.

"We are at a stage now where we need to think seriously about the possibility of military action, and in that context, we are asking our friends and allies to start considering seriously what they could contribute," one American source said.

This does not mean the U.S. will decide soon to go to war with Iraq, the source added.