Prime Minister Junichiro Koizumi predicted today that the Japanese public would come to understand his decision to support the United States in the war with Iraq, but he acknowledged that for now people in his country remain "overwhelmingly against" his position.

In an interview with The Washington Post, Koizumi expressed confidence in his decision, which some analysts and policymakers here say is undermining Japan's decades-long efforts to play the role of pacifist nation in world affairs and strong supporter of the United Nations.

"I believe it's possible to make them compatible," Koizumi said of the choice between the United States and the United Nations, which some in his government had desperately sought to avoid.

Opinion polls show opposition to the war at 65 percent or more, and there have been scattered antiwar demonstrations.

"The people fully understand what kind of danger you're exposed to when the weapons of mass destruction, chemical and biological weapons, fall in the hands of a dangerous despot," Koizumi said in the interview in his office Monday.

"Also, considering Japan's own defense and security, the public knows the importance of the Japan-U.S. alliance," he said. "The Japanese defense capability is not adequate, and with the security pact with the U.S., Japan is defending itself."

After weeks of hedging, Koizumi announced at the start of the war that Japan would back the United States. Japan cannot constitutionally provide troops to the war, but Tokyo's position has earned kudos from Washington; U.S. Ambassador Howard H. Baker Jr. recently was reported to have told senior political figures here that "there are three great leaders in the world now -- [President] Bush, [British Prime Minister Tony] Blair and Koizumi."

Koizumi said he told President Bush that Japan would help pay for the reconstruction of Iraq, though he would not discuss in the interview how large its contribution would be. He indicated Japan would prefer that the reconstruction effort be run by the United Nations. And he said Japanese soldiers could be sent to Iraq as part of a U.N.-sanctioned peacekeeping force after the war "if it's in compliance with the [Japanese] peacekeeping operations law."

Some policymakers here worry that support for the U.S. campaign will doom the effort Japan has made since emerging from postwar poverty to carve out a role in multinational peacekeeping operations through the United Nations.

Koizumi said his decision does not undercut that effort. "I believe the U.S. attack is in compliance with the U.N. Charter. Some do say that it was a preemptive attack. But I think it is in line with U.N. Resolution 1441 and other resolutions," he said. Resolution 1441, passed unanimously by the Security Council in November, authorized the last round of U.N. weapons inspections in Iraq and warned of unspecified consequences if the inspections were impeded.

Polls show that public support for Koizumi's stance on Iraq has been buoyed by rising apprehension in Japan about the threat from North Korea and a concurrent rise in support for staying closely allied with the United States, which provides military protection.

Asked if his reference to a "dangerous despot" with weapons of mass destruction included the North Korean leader, Kim Jong Il, Koizumi replied, "that's related." But noting efforts to find a diplomatic solution to tensions with North Korea, he added, "our response to North Korea may not necessarily be the same as to Iraq."

Koizumi said he believed the danger of hostilities with North Korea over its nuclear programs was "extremely small," and predicted that North Korea "will not actually take the step" of launching a ballistic missile over Japan, as it did in 1998.

He avoided discussing how Japan would respond if North Korea openly developed nuclear weapons, saying, "what is important is for us to make every effort to prevent that from happening."

The Bush administration has taken a harder-line approach to North Korea than its allies in the region, saying that it must dismantle its nuclear programs before any direct talks with Washington can begin. In the interview, Koizumi did not criticize that strategy. "I believe the Bush administration is handling this matter appropriately. As far as I can judge in directly talking to President Bush and Secretary [of State Colin L.] Powell, I positively believe they are responding very judiciously and gently."

Prime Minister Koizumi acknowledged that the Japanese public remains at odds with his backing of U.S.-led war.