The US administration said it approved President Lee Myung-bak's demand that "North Korea immediately apologise and punish those responsible for the attack and most importantly, stop its belligerent and threatening behaviour." He also said that his nation would no longer tolerate the North's 'brutality' and the repressive communist regime would pay for the Cheonan attack.
Lee Myung also decided to cut off all trade relations with the North and to take Pyongyang to the UN Security Council for punishment for the Cheonan attack, which was the country's worst military disaster since the Korean War.
White House also said that Seoul can continue to count on the full backing of the United States.
"US support for South Koreas defence is unequivocal, and the President has directed his military commanders to coordinate closely with their Republic of Korea counterparts to ensure readiness and to deter future aggression," said the White House.
Obama has also ordered US government agencies to review North Korea's policies toward Pyongyang. Robert Gates, the US Secretary of Defence has been in close contact with the South Korean Defence Minister and will meet him next month in Singapore.