North Korea ? North Korea boasted of being a “proud nuclear power” and threatened today to harm the U.S. if attacked as tensions mounted over a possible crackdown on exports of suspected missile parts from the North.

President Barack Obama said the U.S. 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 Sunday 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.