Diplomatic efforts to defuse the North Korean missile crisis collapsed Thursday, as a Chinese mission to Pyongyang failed to produce a breakthrough and talks between the two Koreas ended in acrimony. The failure set the stage for a showdown at the United Nations, where the United States and Japan are pushing for tough action against the secretive state after it launched seven missiles in Japan's direction last week.The top US negotiator on North Korea, Christopher Hill, said during a visit to Beijing that the regime could now expect a "very strong" message after China's efforts to lower tensions in the region failed. "I have talked as much as I can with the Chinese to see what's going on with their mission in Pyongyang. From what I understand, we don't have any breakthroughs in Pyongyang," Hill said before departing for Washington. "So far (the North Koreans) don't seem interested in listening, much less in doing anything to address the situation," said the American diplomat, who has been shuttling among Asian capitals since the tests rattled the region. "I'm confident there will be a very strong, very clear message for the DPRK (North Korea)," Hill said.