North Korea met a U.S. diplomatic overture with a fresh show of force, seemingly testing the Obama administration's resolve for new nuclear talks.
After three years of diplomatic deadlock, the U.S. had appeared receptive to preliminary discussions to assess North Korea's intentions and the prospects of ridding the country of nuclear weapons.
Then came Saturday's claim that North Korea successfully test-fired a newly developed ballistic missile from a submarine. Not long after that announcement, South Korean officials said the North fired three anti-ship cruise missiles into the sea off its east coast.
The State Department said launches using ballistic missile technology are "a clear violation" of U.N. Security Council resolutions. Washington urged North Korea "to refrain from actions that further raise tensions in the region and focus instead on taking concrete steps toward fulfilling its international commitments and obligations."
Just this past week, a South Korean envoy had visited Washington and Beijing as countries involved in long-stalled aid-for-disarmament negotiations with the North mulled their diplomatic options.
Even before the latest flexing of the North's military might, U.S. officials had questioned whether the North was seriously interested in re-engaging on the nuclear issue.
North Korea conducted its first nuclear test in 2006. International penalties were intended to prevent the North from obtaining sensitive technology and starve the country of funds. Yet U.S.-based experts forecast that North Korea could increase its nuclear arsenal from at least 10 weapons today to between 20 and 100 weapons by 2020.
North Korea wants to be recognized as a nuclear power. But a denuclearized Korean Peninsula is the aim of the negotiating process that China, Japan, Russia, South Korea and the U.S. say they want to revive.
The last public U.S. attempt to negotiate a nuclear freeze and get the six-party process restarted collapsed in 2012 after the North launched a long-range rocket.
North Korea conducted its third nuclear test in February 2013, and has test-fired numerous shorter-range missile since then.
The U.S. quietly proposed a meeting with North Korea this January, before the recent U.S.-South Korea military exercises. The two sides, however, failed to agree on who could meet and where.
China, North Korea's traditional benefactor, has pushed for resumption of dialogue. South Korean envoy Hwang Joon-kook, who met separately with his U.S. and Chinese counterparts this past week, said all five parties were ready for talks to understand North Korea's intentions.
The U.S. was willing to be flexible about a format for "serious dialogue," a senior U.S. official said. The official was not authorized to be named and requested anonymity to discuss U.S.-North Korea policy.
Associated Press writer Kim Tong-hyung in Seoul, South Korea, and Cara Anna at the United Nations contributed to this report.