White House press secretary Jay Carney said Monday the U.S. has not detected any military mobilization or repositioning of forces from Pyongyang to back up the threats from North Korean leader Kim Jong Un.
Nonetheless the U.S. has a made a point of publicizing its own recent military moves, including the deployment of bombers and F-22 stealth fighters to South Korea as part of two-month-long military exercises.
And on Monday U.S. officials said a Japan-based U.S. Navy guided-missile destroyer capable of shooting down ballistic missiles had been positioned slightly closer to the Korean peninsula, though still within its usual operating area.
Last month, the Pentagon announced plans to increase by 2017 the number of Alaska-based missile interceptors designed to shoot down any prospective North Korean missile launch aimed at U.S. territory.
Pyongyang has reacted angrily to U.S.-South Korean military drills and a new round of U.N. and U.S. sanctions that followed North Korea's Feb. 12 underground nuclear test.
Carney called the U.S. response "prudent." He noted that such tough talk from North Korea is part of a familiar pattern.
Carney says the White House takes the threats "very seriously." But he says the rhetoric "is consistent with past behavior."