US Secretary of State Hillary Clinton on Saturday warned North Korea to refrain from provocative behaviour and comply with its international obligations.
"It must comply with international law and obligations, live up to its commitments in the Six-Party Joint Statement of 2005, and refrain from provocative behaviour," Clinton said in a statement after the UN Security Council issued a presidential statement that condemned North Korea's attack on the South Korean ship Cheonan.
The Security Council presidential statement sends a clear message that such irresponsible and provocative behaviour is a threat to peace and security in the region and will not be tolerated, she said.
"Attacks on the Republic of Korea are unacceptable and the United States joins the Security Council in calling for North Korea to uphold the Korean Armistice Agreement," said Clinton, who is scheduled to travel to Seoul later this month.
"Today's Security Council action underscores the unity of the international community and the reality that a peaceful resolution of the issues on the Korean Peninsula will only be possible if North Korea fundamentally changes its behaviour," Clinton said.
The commitment of the US to South Korea's security and sovereignty is unwavering, she said, adding that she would be travelling to Seoul later this month for further consultations with South Korean allies.
"We applaud the Republic of Korea's careful handling of this situation and we join the Security Council in again expressing our deepest condolences to the families and friends of the victims of this tragic attack," Clinton said.
Meanwhile, a US think-tank on Friday demanded that the US must signal it will take all necessary measures to defend its critical ally during this time of heightened tensions.
"Given the UN's failure to respond effectively to North Korean aggression, the rest of the world, lead by the US and South Korea, must now take the initiative. Failure to do so will only embolden Pyongyang and its Chinese enablers," said Bruce Klingner, from the Heritage Foundation.
Noting that the US should show its resolve by engaging in extensive joint anti-submarine and mine-clearing naval exercises with South Korea in the West Sea, Klinger said the US should also take the lead in imposing unilateral sanctions on foreign government, business and banking entities complicit in assisting North Korea's nuclear and missile programs.
"The UN Security Council's timid reaction to North Korea's blatant and heinous attack of a South Korea naval ship is extremely disappointing-though not unexpected. China and Russia had been signalling for weeks that they were eager to abandon all concepts of upholding the rule of law and international rules of behaviour in favour of meekly maintaining the peace," he said.
"As for the US Administration, the problem was in not confronting this obstructionism more forcefully and not putting Moscow and Beijing on the diplomatic spot," Klinger said.