North Korea boasted of being a "proud nuclear power" and threatened June 22 to harm the United States if attacked as tensions mounted over a possible crackdown on exports of suspected missile parts from the North.

A South Korean Army soldier sits on a K-9 self-propelled howitzer during a military drill in Yeonchon, South Korea, on June 18. AP PHOTO

U.S. President Barack Obama said the United States is ready to cope with "any contingencies" involving North Korea, and vowed not to "reward belligerence and provocation."

South Korea's YTN news network reported June 21 that a U.S. Navy destroyer tailing a North Korean ship suspected of carrying missiles and related parts was headed toward Myanmar in what could be the first test of new U.N. sanctions against the North over its recent nuclear test.

The sanctions — punishment for an underground nuclear test North Korea conducted May 25 — firm up an earlier arms embargo against North Korea, and authorize ship searches in an attempt to thwart the regime's nuclear and ballistic missile ambitions.

North Korea's main Rodong Sinmun newspaper June 22 called it "nonsense" to say the country is a threat to the United States, and instead claimed Washington was the one threatening the North. The paper also warned in a commentary that the country is prepared to strike back if attacked.

"As long as our country has become a proud nuclear power, the U.S. should take a correct look at whom it is dealing with," the editorial said. "It would be a grave mistake for the U.S. to think it can remain unhurt if it ignites the fuse of war on the Korean Peninsula."