The chief U.S. negotiator on North Korea said Tuesday he and Japanese officials have reaffirmed their nations' cooperation in fully implementing through "concrete action" a U.N. resolution to prevent Pyongyang from conducting more missile tests.

"We talked about the desire to coordinate and implement U.N. Security Council Resolution 1695. We want to make sure we are in sync," Christopher Hill, the top U.S. negotiator for the six-party talks, told reporters at the Foreign Ministry in Tokyo.

"It's very important that (the resolution) be followed up by concrete action that it calls all its member states to take," Hill said, referring to the Security Council resolution unanimously adopted July 16 after North Korea test-fired seven ballistic missiles, including a long-range Taepodong-2 missile, on July 5.