A Musudan launch would defy the United Nations Security Council and the U.S., which has said a missile test would prompt efforts to place further UN penalties on North Korea, already under sanctions for previous missile and nuclear tests. After the Security Council imposed additional sanctions last month in response to a third nuclear test, Kim's regime responded by cutting a hotline with South Korea and threatening a preemptive nuclear strike.
Kerry is due in the region next week for talks with leaders in Seoul, Beijing and Tokyo. The U.S. supports South Korea with about 28,500 troops stationed in the country plus a force that includes about 38,000 U.S. military personnel in Japan, a major air base in Guam, and global strike capabilities with air- and sea-launched ballistic missiles and cruise missiles carried on aircraft, surface ships and submarines.
The U.S. is looking for China, North Korea's largest trade partner, to use its leverage to persuade Kim to back down. China, having failed to get Kim to call off his last nuclear test, voted in favor of UN sanctions last month, and the U.S. wants the government in Beijing to do so again if North Korea tests another missile or nuclear device.
North Korea "has been the subject of intense conversations between the secretary and his Chinese counterparts," Nuland said.
"It'll be a central focus of the secretary's diplomacy when he's in Beijing to see what more we can do to get the attention of the leadership in the DPRK and get them to change course,' she said. DPRK refers to the country's official name, Democratic People's Republic of Korea.
Speaking at an event in Seoul March 26, former Secretary of State Colin Powell played down the likelihood of war breaking out on the Korean peninsula.
''I do not see the prospect of conflict as some of my friends in the United States do," he said. "They bluster, they threaten, they say things they cannot do."
— With assistance from Margaret Talev in Washington and Sangwon Yoon, Seyoon Kim and Saeromi Shin in Seoul.