TOKYO (AP) — U.S. national security adviser John Bolton has called a series of short-range missile tests by North Korea last month a violation of U.N. Security Council resolutions and says sanctions must be kept in place.

Bolton said Saturday in Tokyo that the U.S. position on the North's denuclearization is consistent and that a repeated pattern of failures to rid North Korea of nuclear weapons should be stopped.

His comment comes a day after North Korea's official media said nuclear negotiations with Washington won't resume unless the US. abandons what Pyongyang describes as unilateral disarmament demands.

President Donald Trump arrives in Tokyo later Saturday for a four-day visit largely highlighting close ties with Japanese Prime Minister Shinzo Abe.