US and South Korean leaders meet Tuesday to coordinate action in an escalating showdown with North Korea, with President Barack Obama expected to try to reassure the US ally of security commitments.
President Lee Myung-Bak's visit to Washington was planned well ahead of the North Korea crisis and aimed in part at smoothing out relations after Obama in his campaign rejected a hard-negotiated free-trade deal with Seoul.
The global economic crisis, which has hit South Korea hard, is also expected to be on the agenda between the two nations whose alliance has dramatically broadened in recent years to include working together on Iraq and Afghanistan.
Obama "looks forward to exploring ways in which the two countries can strengthen cooperation on the regional and global challenges of the 21st century," said Robert Gibbs, the White House press secretary.
But North Korea is set to take center-stage after the hardline communist state tested a nuclear bomb and long-range missile and stormed out of a six-nation disarmament agreement.
The UN Security Council voted unanimously Friday to toughen sanctions on North Korea, leading some experts and officials to fear Pyongyang will carry out another nuclear test in retaliation.
Lee, who starts his talks Monday meeting Secretary of State Hillary Clinton, has enraged the impoverished North by refusing aid without progress in the nuclear and other rows reversing a decade of liberal policies by Seoul.