Washington: The United States is in consultation with South Korea, which is formulating the next step against Pyongyang after Seoul accused it of indulging in act of aggression by sinking the Cheonan naval warship.
The statement by the White House comes just a day after South Korean government concluded that a North Korean torpedo was responsible for the March 26 naval ship sinking that killed its 46 sailors.
"We are in consultation directly with the South Koreans as they make their next set of decisions," White House Press Secretary Robert Gibbs said at his daily press briefing on Thursday.
"In addition to the South Koreans, we have been in touch with neighbouring countries. We have been in touch with bodies of the international community," he said.
Gibbs also held North Korean "actions" for its isolation from the international community.
"That`s what resulted in a very strong set of sanctions last year," Gibbs said.
"I think this act of aggression, this clear violation of the armistice agreement further sets them back and further isolates them," he said in response to a question.
Meanwhile, reflecting the views of the lawmakers, Senator Joseph Lieberman called for strong, unequivocal support for South Korea in response to North Korea`s alleged attack on South Korean warship Cheonan.
"The United States and our allies must now provide strong, unequivocal support to South Korea in response to this outrageous attack, and together formulate a firm, united, and coordinated response," the Senator said.
Lieberman said that the response of the US and the world to the attack would have "extremely important strategic consequences far beyond Northeast Asia".
"This is a test of whether a rogue regime, hiding behind its nuclear arsenal, can attack a democratically of the United States with impunity. It is imperative that both our friends and our enemies understand that we will not allow that to happen," he said.
US Secretary of State Hillary Clinton`s three-nation Asia tour to Japan, China and South Korea is likely to be dominated by the new crisis with North Korea, State Department spokesman PJ Crowley conceded but he ruled out any unilateral steps against Pyongyang at this point of time.
"We will be consulting closely. I think one of the hallmarks of our policy towards North Korea over the past 15 months has been the strong consensus that we have had and maintained with China, with Russia, with Japan, with South Korea, on this process," Crowley said.
"It was a matter that after a series of provocative steps with North Korea last year, the Council acted aggressively and affirmatively in passing 1874. We`ve seen over many months aggressive implementation of 1874 and other resolutions," the spokesman said.
"So there are tools that are already available to us."
Crowley said that the US is searching for other steps against Pyongyang but will "do this in close consultation" with the country`s partners.
Terming ship sinking as "deliberate", the official said that South Korea is a "very close" ally of the US and both the countries share interests and responsibilities.
"We will continue to support South Korea through this. We will be guided by actions that South Korea wishes to take. We all have a mutual interest in a stable and peaceful and secure Korean Peninsula. In that regard, there are clearly things that North Korea must do," Crowley said.
The US State Department also warned North Korea that its "provocative" actions would not be tolerated and there would be "consequences”.
The State Department spokesman said there are things that they definitely want North Korea to do.
"Certainly, ceasing the string of provocative actions that undermine peace and security in the region is fundamental.”
"They have a range of responsibilities under the 2005 agreement and other responsibilities, and North Korea must fulfil those responsibilities if they have any hope of changing their relationship with the United States or other countries in the region," he added.