SEOUL, South Korea >> Diplomats from the United States, South Korea and Japan met in Seoul on Wednesday to discuss policy responses to North Korea’s accelerating efforts to expand its nuclear weapons program.

Before flying to Seoul for talks with South Korean Vice Foreign Minister Lim Sung-nam, U.S. Deputy Secretary of State John Sullivan and Japanese Deputy Foreign Minister Shinsuke Sugiyama met in Tokyo today and vowed to find more ways to apply pressure on Pyongyang.

The vice-ministerial discussions will be followed by a meeting between the countries’ top envoys for the currently stalled nuclear disarmament talks with North Korea that also involved China and Russia. The six-party meetings were last held in late 2008 and the North went on to conduct its second nuclear test in May 2009.

The Seoul talks came as the United States and South Korea held joint naval drills involving fighter jets, submarines and other naval vessels, including the aircraft carrier USS Ronald Reagan, to train for potential North Korean provocations. The allies regularly conduct joint exercises that Pyongyang condemns as invasion rehearsals.

North Korea in recent months has tested purported thermonuclear weapons and intercontinental missiles and flew two midrange missiles over Japan while also threatening to fire the same weapons toward Guam, a Pacific U.S. territory and military hub.

After his meeting with Sugiyama in Tokyo today, Sullivan said that that the focus at the State Department is still on diplomacy to solve the problem and eventually denuclearize the Korean Peninsula.

“We must, however, with our allies in Japan and South Korea and elsewhere, be prepared for the worst should diplomacy fail,” he said, adding that the United States must be prepared to defend itself and its allies.

South Korean Foreign Ministry spokesman Noh Kyu-duk said ahead of the Seoul meetings that the allies are committed to “stably managing the situation” and pursuing all available avenues for North Korea’s denuclearization, including efforts to bring Pyongyang back to the negotiating table.

North Korea’s deputy U.N. ambassador, Kim In Ryong, said today at the United Nations that his country plans to conduct more satellite launches, which outside governments see as a cover for banned tests of missile technologies.

On Monday, Kim told the U.N. General Assembly’s disarmament committee that the situation on the Korean Peninsula had “reached the touch-and-go point and a nuclear war may break out any moment,” citing the U.S.-South Korea drills and what he called U.S. plans to remove the North’s leadership. He said the North has the right to possess nuclear weapons in self-defense.