North Korea, facing international pressure to abandon its nuclear program, marked the communist country's 61st anniversary Wednesday with a vow to "mercilessly annihilate the U.S. imperialists" if they attack.

North Korean state TV played patriotic songs calling for eternal loyalty to leader Kim Jong Il for building a "paradise" on the Korean peninsula, while the country's main newspaper issued a lengthy editorial pledging to defeat any U.S. aggression.

"Today, the U.S. imperialists and other enemies are increasingly running amok over its new war plot to stifle our republic with its forces," the Rodong Sinmun editorial said. If the U.S. attacks, the North will "mobilize all military strengths and mercilessly annihilate the aggressors."

It also praised Kim's "military first" policy, under which he has devoted much of the impoverished country's scarce resources to his 1.2 million-member army, making it one of the world's largest.

"The military power is the centerpiece of the national strength and we cannot think about our country's prosperity without powerful guns," the paper said.

The anniversary of the country's founding is a major holiday in North Korea, along with the birthdays of the leader and his father, late founder Kim Il Sung.

North Koreans streamed to Mansu Hill in Pyongyang on Wednesday to lay flowers and bow before a towering statue of Kim Il Sung, footage from television news agency APTN showed. Women in colorful traditional "hanbok" dresses danced at a plaza near the city's Daedong River.

"The people seem very happy, they seem very respectful and very peaceful," Hakan Sokmensuer, an American tourist from Florida, told APTN.

A year ago, Kim Jong Il's failure to appear at a massive military parade for the country's milestone 60th anniversary sparked feverish speculation about his health and concern that his sudden death could trigger a succession crisis in the nation he rules with absolute authority.

U.S. and South Korean officials later said Kim was believed to have suffered a stroke. However, the 67-year-old leader appears to have recuperated and remains in charge, U.S. and South Korean officials said.

The anniversary comes at a time of heightened tensions over North Korea's nuclear defiance, following its abandonment of a 2007 disarmament-for-aid pack and pullout from talks with the U.S., South Korea, China, Russia and Japan.

Earlier this year, North Korea earned international condemnation for conducting nuclear test, launching a rocket and test-firing a barrage of missiles. However, the regime has reached out to Washington and Seoul in recent weeks by releasing detained Americans and South Koreans and reportedly inviting U.S. officials to Pyongyang for one-on-one talks.

The U.S. has said it would meet the North Koreans — but only in the context of the now-stalled six-nation disarmament negotiations.

The U.S. is open to engaging North Korea, but Pyongyang must signal it is willing to commit to an "irreversible process of complete and verifiable denuclearization," Glyn Davies, chief U.S. envoy to the International Atomic Energy Agency, said Tuesday in Vienna.