Japanese Prime Minister Junichiro Koizumi has thrown his support behind the United States and Britain despite widespread opposition to war in Japan.
Tens of thousands of people have been out on the streets of Tokyo to protest against war in Iraq, but in a televised news conference this week, Mr Koizumi repeatedly stressed the importance of maintaining the 50-year-old alliance with the United States.
Tokyo's support for President Bush is not motivated by fear of Iraq, but by a much more immediate threat - the prospect of a nuclear armed North Korea.
Many Japanese are against military action
Junichiro Koizumi knows he will need American protection in the event of conflict.
"The United States says it regards an attack on Japan as an attack on itself," Mr Koizumi said.
"That's a very strong deterrent for North Korea, but we should also show our determination to defend the country with our own hands. We need to have laws in place to handle an emergency," the Japanese leader added.
North Korea is working on two separate nuclear programmes and could be just months away from building an arsenal of atom bombs.
It also has stockpiles of chemical and biological weapons and the missiles to deliver them.
Japan's vulnerability was underlined when the defence minister said a pre-emptive strike would be justified if North Korea was preparing an attack - but he then conceded that Japan did not have the capability to deliver it.
Whatever the misgivings about war in Iraq, the alliance with Washington is stronger than ever
Japan's military is one of the most modern and best equipped in the world, but its aircraft are restricted to home territory because they cannot be refuelled in flight and they have no ground attack capability.
The Japanese constitution also imposes severe restrictions.
Intelligence reports say North Korea is preparing to test a ballistic missile over Japan to show off its offensive capability, but Japan's defence forces can only sit and watch.
Ichita Yamamoto, of the ruling Liberal Democratic Party, said there would be pressure for economic retaliation if the test went ahead.
"I think Japan should step up economic sanctions against North Korea, namely halting the stream of money and people, particularly we are thinking to limit the trade between the two countries," Mr Yamamoto said.
North Korea has said repeatedly that sanctions would be tantamount to a declaration of war.
So Japan will need American backing if it is going to put the squeeze on the communist state.
Some in the region believe nothing can now stop North Korea going nuclear.
But Japanese diplomat Shunji Yanai says Tokyo cannot accept that.
"That is really a nightmare and we have to do everything possible to stop it," he said.
"They have already mobile missiles. There may be 100 or 200 mobile missiles that are already deployed and that can reach Japan," he added.
A nuclear Japan?
If North Korea does test a nuclear weapon, there are warnings that Japan will be tempted to follow suit, but most Japanese remain deeply opposed to nuclear weapons.
Former General Toshiyuki Shikata said a nuclear armed Japan would face disaster.
"We depend (for) almost 100% of (our) energy resources on the Middle East, and 60% of food are from the outside of Japan so if Japan changes the policy, we will be facing a very severe sanction, so we cannot survive," he warned.
Japan is rapidly upgrading its forces because of the threat from North Korea.
This month it will launch spy satellites for the first time, and high-tech warships are being deployed to the sea between Japan and the Korean peninsula - but the American nuclear umbrella and the presence of US troops has never seemed more important.
Whatever the misgivings about war in Iraq, the alliance with Washington is stronger than ever.