U.S. Secretary of State Hillary Clinton arrived for talks with South Korean Foreign Minister Kim Sung-hwan on Saturday and President Lee Myung-bak on Sunday, before a trip to Japan in a gesture of support following last month's earthquake and tsunami disasters that killed thousands and crippled a nuclear plant.
The shift in focus to Asia follows Clinton's attendance at a NATO conference in Berlin where the alliance's foreign ministers faced strains over a Western air campaign in Libya against forces loyal to Muammar Gaddafi.
U.S. and South Korean trade negotiators struck a deal in December on a free trade pact, which was signed in 2007 but had not been ratified for three years because of U.S. auto and beef industry concerns.
However, both the U.S. Congress and the South Korean have yet to pass bills to approve the pact.
"I'm very encouraged and determined about the passage of the free trade agreement," said Clinton, sitting alongside Kim in Seoul. "We will be consulting and making the case together to our respective legislatures and I'm very confident there will be a positive outcome that will benefit both of our countries.
"It is important that we're meeting in the home stretch of the Korean free trade agreement."
Sander Levin, the top Democrat on the House of Representatives Ways and Means Committee, last month criticised Republicans for refusing to move ahead on the Korea agreement until the White House sends Congress implementing bills for two other long-delayed trade agreements with Colombia and Panama.
Republicans broadly support the Korea agreement, but have threatened to block a vote on the pact unless the White House also submits the Colombia and Panama deals for approval.
U.S. Trade Representative Ron Kirk has said the Obama administration wants to win congressional approval of a free trade agreement before July.
The agreement is currently pending in South Korea's parliament and is expected to be passed.
The U.S. International Trade Commission estimated in 2007 that the Korean agreement would boost U.S. exports by about $10-11 billion annually, while increasing imports from that country by about $6.5-7.0 billion.
Clinton's visit also comes amid a diplomatic flurry that could bring renewed efforts to resume long-stalled six-nation talks with Pyongyang aimed at curbing its nuclear weapons ambitions. A South Korean nuclear envoy was in Washington this week meeting senior U.S. officials. North Korea has slipped down U.S. President Barack Obama's policy agenda recently as he has focused heavily on turmoil in the Middle East, including the Libya conflict, and economic and budget problems at home.
Pyongyang has said it wants to return to nuclear talks, but Seoul and Washington have questioned its sincerity -- pointing to revelations in November about major advances in Pyongyang's uranium enrichment programme.
The Obama administration wants to reassure South Korea of its security commitment and that Seoul will be consulted on any moves toward renewing six-party talks.
"I would like to express our deep appreciation for your steadfast support and close coordination with us in dealing with North Korean issues," South Korea's Kim said.
North Korea's latest overtures follow a recent spate of hostile actions, including the shelling of a South Korean island on Nov. 23 and its suspected sinking of a South Korean ship just over a year ago. Pyongyang had promised to abandon its nuclear programs under a 2005 aid-for-disarmament deal that collapsed amid accusations on both sides that neither kept its end of the bargain. The North tested nuclear devices in 2006 and 2009 and has also conducted long-range missile tests.