North Korea could face "tougher measures" from the international community if it doesn't quit its pursuit of nuclear weapons, President Bush and Japanese Prime Minister Junichiro Koizumi (search) said Friday.

The two leaders, meeting at the president's ranch in Texas, did not say specifically what those measures would be, but agreed that something must be done to stem Pyongyang's thirst for nuclear weapons.

"We are confident that our diplomatic approach will bring a peaceful solution. Yet we agreed that further escalation of the situation by North Korea will require tougher measures from the international community," Bush told reporters.

Bush said he and Koizumi view the crisis "exactly the same way" and that neither will tolerate nuclear weapons in North Korea (search).

"We will not give in to blackmail," Bush said. "We will not settle for anything less than the complete, verifiable and irreversible elimination of North Korea's nuclear weapons program."

Koizumi echoed Bush, saying Pyongyang must "promptly and completely eliminate all nuclear weapons programs."

"North Korea will have to understand that threats and intimations have no meaning whatsoever," the Japanese leader said.

North Korea pulled out of the Nuclear Nonproliferation Treaty (search) earlier this year and kicked out weapons inspectors. It acknowledged that it is in the process of reconstituting its nuclear weapons missile program.

Bush and Koizumi met up at the ranch on Thursday afternoon where the prime minister was treated to a quiet dinner and a tour of the grounds. On Friday, business meetings included discussions on both nations' economies, the peaceful rebuilding of Iraq and Afghanistan and the United States' development of ballistic missile defense systems.

Koizumi's response to North Korea’s actions is exactly what the Bush administration had hoped to elicit. The White House has been trying to convince North Korea's neighbors that heavy pressure is the only way to deal with the rogue nation.

For his part, Koizumi wants North Korea to account for the abduction of Japanese nationals by North Korean forces in the late 1970s and early 1980s. Japan has said that ties with North Korea can never be normalized without that issue being settled. Bush said he agreed with that perspective.

"I assured the prime minister that the United States will stand squarely with Japan until all Japanese citizens kidnapped by North Korea are fully accounted for," Bush said. "I strongly condemn the kidnapping of Japanese citizens by the North Koreans."

Bush said he is trying to organize future talks with Koizumi that would also include South Korea.

"Coordination among Japan, the United States and the Republic of Korea is crucial" to a peaceful solution, Koizumi said.

Earlier this month, Bush and South Korean President Roh Moo-hyun issued a joint statement declaring they would not tolerate atomic weapons in North Korea and would consider further steps to prevent them if diplomacy fails.

Bush added that he would also like China's participation in "ensuring that the peninsula is nuclear weapons-free."

Last month, the administration said that it would not be subjected to blackmail by North Korea. North Korean officials speaking with U.S. diplomats in Beijing last month said the country would quit its nuclear and missile programs in exchange for economic aid and security guarantees.

Japan and the United States also have the backing of the other members of the Group of Eight industrialized countries and Russia, who while meeting in Paris Friday, issued a statement urging North Korea to begin the "full, prompt, verifiable and irreversible dismantlement" of its nuclear program. The foreign ministers of the G-8 countries also suggested that the Beijing talks be expanded in the future to include South Korea, Japan and Russia.

Leaders are also trying to get rid of other bad habits in North Korea, including a suspected drug trade and illegal missile exports. Koizumi said Japan "will crack down more vigorously on illegal activities" by North Korea.

The two leaders appeared to have worked on their personal ties while visiting together. Koizumi said before the summit that better relations was one of his goals in the talks.

"Thankfully, I could get a good amount of time (for the talks), so I think we can discuss various matters in a candid, frank and thorough manner," Koizumi told reporters as he flew to America.

The Associated Press contributed to this report