President Lee Myung-bak will be feted at the White House and become the first South Korean leader in 13 years to address a joint meeting of Congress — cementing his standing as President Barack Obama’s staunchest ally in Asia.

The Obama administration says the pact will generate $11 billion in annual US exports and 70,000 jobs, boosting the US trade agenda in the economically vibrant Asia-Pacific region.

It also will elevate the US-South Korean alliance, traditionally defined by their common enmity of communist-governed North Korea. More than 28,000 US troops remain based in South Korea as a deterrent.

“The free trade agreement really does take this relationship to the next level,” said Victor Cha, who served as White House director of Asian affairs under President George W. Bush.

Under Obama, efforts to engage more in Asia have had their ups and downs. The key relationship with Japan has suffered from Tokyo’s conveyor belt of prime ministers, and the US has struggled to realize an effective, strategic alliance with India.

Relations with South Korea have been far more straightforward. Seoul has proved a willing helper on US foreign policy priorities such as Afghanistan and combating climate change.

The allies have moved in lockstep in their diplomacy toward North Korea, which was accused of launching two military attacks in 2010 that sank a South Korean submarine and killed 50 South Koreans, almost sparking another war on the divided Korean Peninsula.

Obama and Lee have refused to offer fresh aid and incentives to North Korea without it taking concrete action to show it is sincere about eventually giving up its nuclear weapons.

That policy of “strategic patience” and reluctance to jump back into negotiations has come in for criticism. While multinational disarmament talks have been suspended, North Korea has unveiled a uranium program that gives it a new means of generating fissile material for atomic bombs.

In recent months, however, both Seoul and Washington have held exploratory talks with Pyongyang, helping dial down tensions.

The United States is expected to hold another meeting with North Korea soon, to discuss how the six-nation disarmament-for-aid negotiations can get back on track. Although it is thought very unlikely Pyongyang would ever give up its nuclear weapons, talks are seen as a way of forestalling fresh aggression by the North.

Both South Korea and the United States are entering an election year, and will want to avoid the kind of security crisis that could ensue following a nuclear test or military attack.

While Lee and Obama will be discussing next steps on North Korea during their meeting, the main theme of the visit remains trade.

After hosting Lee at a White House state dinner Thursday night, Obama will travel with the South Korean leader to a General Motors plant in Detroit, the heart of the US auto industry.

The free trade pact was first agreed by the two governments, and has taken four years to near fruition because of the Obama administration’s demand for US access to South Korea’s auto market.

Negotiators reached a compromise late last year, and Lee’s visit spurred Democrats and Republicans to set aside their differences and approve free trade agreements with South Korea, Panama and Colombia. Lawmakers of both parties want to show they are taking action to stimulate the sluggish US economy and create jobs.

The Korean pact, which still requires approval from South Korea’s legislature, is America’s biggest free trade agreement since the 1994 NAFTA pact with Canada and Mexico. Lee said Wednesday it sends a powerful message to the world that the US and South Korea are opposed to protectionism and support free and open trade.

South Korea is the world’s 12th largest economy. US-South Korea trade amounted to $90.2 billion last year.