Senior diplomats from Japan, the United States and South Korea pledged Wednesday to take "specific steps" if North Korea conducts a nuclear test, a Japanese Foreign Ministry official said, with fears growing about such a provocation.

The agreement came at a trilateral meeting in Tokyo between Takehiro Funakoshi, director general of the Japanese Foreign Ministry's Asian and Oceanian Affairs Bureau, and his U.S. and South Korean counterparts, Sung Kim and Kim Gunn.

They also agreed to keep promoting security cooperation among the three nations to beef up their deterrence against North Korea, which has test-launched ballistic missiles in defiance of a spate of U.N. Security Council resolutions, according to the ministry.