North Korea upped its rhetoric on Thursday, vowing to enlarge its atomic arsenal and warning of a "fire shower of nuclear retaliation" in the event of a US attack.
The jingoist statements come as the regime marked the 1950 outbreak of the Korean War.
Meanwhile, the US Navy followed a North Korean ship suspected of carrying weapons in violation of a UN resolution punishing Pyongyang's May 25 nuclear test, and as anticipation mounted that the North might test-fire short- or mid-range missiles in the coming days.
President Barack Obama extended US economic sanctions against North Korea for another year Wednesday, saying the North's possession of "weapons-usable fissile material" and its proliferation risk "continue to pose an unusual and extraordinary threat" to the United States, according to the White House Web site.
