Obama pledges U.S. support for South Korea's defense

WASHINGTON (Reuters) - U.S. President Barack Obama assured South Korean President Lee Myung-bak on Monday of Washington's "unequivocal commitment" to the defense of South Korea following a nuclear test by North Korea.

The two presidents, in a telephone conversation, "also agreed to work closely together to seek and support a strong United Nations Security Council resolution with concrete measures to curtail North Korea's nuclear and missile activities," the White House said in a statement.

Obama also spoke by phone with Japanese Prime Minister Taro Aso and assured him of Washington's "unequivocal commitment to the defense of Japan and maintaining peace and security in Northeast Asia," the White House said.

The U.N. Security Council on Monday condemned North Korea's nuclear test, but Pyongyang looked set to ratchet up tension further with a report it would launch more short-range missiles.

"Our army and people are fully ready for battle ... against any reckless U.S. attempt for a pre-emptive attack," the North's KCNA news agency said.

In a unanimous statement adopted after Monday's nuclear blast, the Security Council decided to start work immediately on a new resolution, condemning the test as a "clear violation" of a previous resolution banning such tests in 2006.

The White House said Obama and Aso agreed to intensify coordination with South Korea, China and Russia and to work closely in the UN Security Council to obtain a resolution with "concrete measures" to curtail North Korea's nuclear and missile activities.

(Reporting by Doug Palmer; Editing by Peter Cooney)