Japan has come out strongly in favour of the US and UK position on Iraq in recent days.
The prime minister, Junichiro Koizumi, has been calling Security Council members to try to persuade them to support a new resolution.
But with public opinion overwhelmingly opposed to war without UN backing, the government finds itself in an increasingly difficult position.
Many Japanese are against military action
Japan likes to see itself as a champion of peace in the world.
Its own pacifist constitution explicitly renounces the right to wage war.
And yet the Japanese Government strongly supports the Americans and British over Iraq.
It is actively trying to win over swing votes on the Security Council.
Mr Koizumi is eager to show the United States he is doing all he can to help - within the limits of the constitution.
Most analysts believe he has little choice.
Japan depends on United States forces for its own security
and the growing nuclear threat from North Korea has reminded the Japanese of their own acute vulnerability.
Still there is a political price to pay. Opinion polls show 80% of the public oppose war in Iraq without UN backing.
Despite his diplomatic initiative, Mr Koizumi has been deliberately vague at home - and has failed to articulate a coherent policy.
Pressed to explain whether he would support a war, the prime minister told opposition politicians it would depend on the mood.
Faced with ridicule in the media, he later said Japan would decide its stance after watching the Security Council and the actions of other governments.
For all the evasion most Japanese expect the government to back the United States shortly after hostilities break out.