A U.S. government delegation is in Tokyo to begin a series of talks throughout Asia on how to respond to North Korea's latest nuclear test.

U.S. Deputy Secretary of State James Steinberg is leading the group, which arrived in Japan Sunday afternoon.  He told reporters on arrival that he expects "very productive and intensive" conversations.

The delegation includes Stuart Levy, who is the U.S. Treasury Department's undersecretary on terrorism and financial intelligence, and Stephen Bosworth, the U.S. special representative for North Korean policy.

From Japan, the delegation travels to South Korea, China and Russia.  Those countries are part of stalled negotiations aimed at ending North Korea's nuclear program.

Later Monday, Steinberg is to meet with Japan's Foreign Minister Hirofumi Nakasone.

North Korea has threatened to take retaliatory action if the United Nations Security Council imposes new sanctions.

Pyongyang said it tested a nuclear weapon underground on May 25, then launched several short-range missiles and renounced the armistice that ended the Korean War in 1953.

U.S. officials say North Korea may be planning to launch more long-range missiles soon.

Some information for this report was provided by AFP and AP.