The United States, Japan and South Korea are sending a clear message with their coordination on policy towards North Korea, a senior US official said on Wednesday, despite some recent friction between the two Asian allies.

"That close coordination sends a very critical message to North Korea in that we are together and shoulder-to-shoulder in our approach to this policy," US Deputy Secretary of State Wendy Sherman told reporters after meeting the vice foreign ministers of Japan and South Korea.

The three-way talks were held in Tokyo despite frayed relations between Japan and South Korea, largely a result of recriminations...