S. Korea's Lee heads to summit with Obama

APTOPIX South Korea Koreas Nuclear
South Korean protesters burn North Korean national flags during a June 14 rally, denouncing the ninth anniversary of the June 2000 summit between former South Korean President Kim Dae-jung and North Korean leader Kim Jong Il in front of Kim Dae-jung's house in Seoul, South Korea.Lee Jin-man / AP
/ Source: The Associated Press

South Korea's president said Monday that the country's alliance with the United States is key to resolving North Korea's nuclear and missile threats as he flew to Washington for a summit with President Barack Obama.

The summit scheduled for Tuesday comes in the wake of North Korea's declaration over the weekend that it would step up its bomb-making atomic program. It also threatened war with any country that tries to stop its ships on the high seas under new sanctions approved by the U.N. Security Council in response to its May 25 nuclear test.

"We cannot stress enough the importance of diplomacy at a time when a security crisis is intensifying due to North Korea's nuclear and missile threats," Lee told a regular radio speech before his departure.

"In particular, the South Korea-U.S. diplomacy is key to that diplomacy," he said. "I will use this summit to reconfirm the strong Korea-U.S. alliance."

The strong ties between South Korea and the United States are a thorn in the side of North Korea, which accuses the two countries of plotting to attack it and topple its communist regime.

The U.S., which denies any such ambitions, has 28,000 troops stationed in South Korea to protect it from North Korea. Pyongyang says it is committed to building atomic bombs and has been developing missiles capable of striking Japan and the United States. It says the two programs are a deterrent against the United States.

Tension on the Korean peninsula spiked after North Korea said Saturday that it would "weaponize" all its plutonium and acknowledged the existence of a long-suspected uranium enrichment program for the first time. Both plutonium and uranium are key ingredients of atomic bombs. North Korea is already believed to have enough plutonium for at least half a dozen atomic bombs.

The United States says it is worried that the impoverished North Korea will sell its nuclear technology to rogue nations, spreading the nuclear threat in the world.

The new U.N. sanctions are aimed at depriving the North of the financing used to build its nuclear program. They also authorize searches of North Korean ships suspected of transporting illicit ballistic missile and nuclear materials.