SEOUL ( United States places warship off Korean coast as a shield for missile attack )

SEOUL (Reuters) - The United States has positioned a warship off the Korean coast as a shield against ballistic missile attack as South Korea's new president vowed swift retaliation against a North Korean strike amid soaring tensions on the peninsula.
But Washington also said it had seen no worrisome mobilization of armed forces by the North Koreans despite bellicose rhetoric over a ramping up of international sanctions against Pyongyang over nuclear weapons tests.

"If there is any provocation against South Korea and its people, there should be a strong response in initial combat without any political considerations," South Korean President Park Geun-hye told the defense minister and senior officials.

North Korea says the region is on the brink of a nuclear war in the wake of U.N. sanctions in response to its February nuclear test and a series of joint U.S. and South Korean military drills that have included a rare U.S. show of aerial power.

In Washington, the White House has said the United States takes seriously North Korea's war threats. But White House spokesman Jay Carney said on Monday: "I would note that despite the harsh rhetoric we are hearing from Pyongyang, we are not seeing changes to the North Korean military posture, such as large-scale mobilizations and positioning of forces."