U.S. President Barack Obama has instructed his military commanders to closely cooperate with South Korea to ensure readiness and to deter future aggression from North Korea.

The White House on Sunday issued a statement expressing full U.S. support for President Lee Myung-bak's public statement on Seoul’s response to the Cheonan incident.

White House spokesman Robert Gibbs said in the statement that Obama ordered his government to review policies on North Korea in order to better deal with the North's provocations and violations of international laws.

The statement also said that the U.S. supports Lee's plan to send the Cheonan case to the United Nations Security Council and will cooperate with its allies to reduce threats from North Korea.