A top North Korean military official renewed Pyongyang's threats of war against what its chief of staff termed the traitors in the South and its allies Wednesday, even as China warned against further provocation on the tense peninsula.

In a speech to mark North Korea's “Army Day,” Vice Marshal Ri Yong-ho said his country is armed with weapons that are capable of destroying the U.S. military “in a single blow.” He also vowed to “cut the throats” of anyone who defames Pyongyang's leadership.

North Korea has stepped up its militant rhetoric against Seoul after South Korean President Lee Myung-bak criticized the North for spending money on its failed rocket launch earlier this month instead of feeding its starving population.

Chinese Vice Foreign Minister Cui Tiankai on Wednesday urged North Korea not to carry out any acts that would escalate tensions in the region.

“China will oppose anything that might jeopardize peace and stability on the Korean peninsula and in Northeast Asia, as this would damage China's national security interests and in the interest of the relevant parties, as well.”

In Washington, U.S. State Department spokeswoman Victoria Nuland said the United States has been working closely with the Chinese, encouraging them to use their influence to persuade Pyongyang to change course. Nuland said statements of this kind are most welcome and that Washington looks forward to consulting with the Chinese on “what more could be done when Secretary [Clinton] and Secretary Geithner are in Beijing for the Strategic and Economic Dialogue next week.”

Many observers fear that the North may carry out its third nuclear test in an attempt to divert attention from the failed rocket launch. It previously conducted nuclear tests after rocket launches in 2006 and 2009.

But the South's Unification Ministry spokeswoman said Wednesday Seoul has detected no unusual military movement from its neighbor and that there is no indication North Korea has carried out a nuclear test.

“There are various reports regarding a nuclear experiment (in North Korea). We are keeping our eye on them, but there is nothing special detected so far. But we are paying close attention.”

South Korean authorities went on high alert this week after North Korea threatened to carry out “special military action” with “unprecedented means and methods.”

Demonstrators have marched in each country to denounce each other's government. Protesters in Seoul burned North Korean flags and chanted anti-Pyongyang slogans Wednesday, while North Koreans recently destroyed effigies of the South's President Lee.