CAMP DAVID, Md. - President Bush and Japanese Prime Minister Shinzo Abe yesterday threatened stronger punitive actions against North Korea if it reneges on a promise to padlock its sole nuclear reactor.

"Our patience is not unlimited," said Bush, standing beside Abe at the Camp David presidential retreat, where they stressed the strength of U.S.-Japan relations.

Eager to show that the two nations stood united against Pyongyang, Abe said: "Should the North Koreans fail to keep their promise, we will step up our pressures on North Korea, and on that point again I believe we see eye to eye."

In February, North Korea pledged during six-party talks with the United States, Japan, China, Russia and South Korea to shut down its reactor by April 14, a deadline that passed almost two weeks ago.

North Korea says it is waiting to receive $25 million in funds frozen after Washington blacklisted a Macau bank for alleged complicity in North Korean money-laundering and counterfeiting.

Critics of the agreement viewed the U.S. decision to allow the return of the $25 million as evidence Bush was softening his stance against North Korean leader Kim Jong Il to resolve the nuclear standoff.

With Defense Secretary Robert M. Gates, Secretary of State Condoleezza Rice, and Christopher Hill, the lead U.S. negotiator in the North Korea talks, looking on yesterday, Bush described his policy on North Korea as "wise," not "soft."

Bush said that if Kim found another reason to backtrack on his pledge, the United States would seek more sanctions against the communist regime. Abe said existing Japanese food and economic sanctions would worsen if North Korea continued to defy the international community.

Abe said he also talked to Bush about Japanese citizens abducted by North Korea in the 1970s and 1980s. Pyongyang sent home five of the 13 people it admitted having abducted, but insisted the rest were dead.

Japan has demanded proof and says more of its citizens might have been taken. Until the issue is resolved, Tokyo has refused to provide energy and economic aid to North Korea or to normalize relations.

"With regard to the abduction issue," Abe said, "President Bush once again expressed his unvarying commitment to support the government of Japan."

Abe's two-day visit to the United States - his first visit since becoming prime minister in September - was designed to show the strength of U.S.-Japanese relations, which have gained more importance as rival China amasses economic and military might.

Bush invited Abe to the presidential retreat in Maryland's Catoctin Mountains in part to thank Tokyo for its support in Iraq and Afghanistan. Bush said he hoped Abe could visit his Texas ranch, which the president called his "little slice of heaven."

A brief one-on-one session between the leaders, who decided to be on a first-name basis, turned into a 35- to 40-minute session in the president's private study in Laurel Cabin, according to a senior U.S. official who attended the larger gathering of U.S. and Japanese officials that followed.

"Shinzo and I": Read Bush and Abe's remarks via EndText