South Korean sources say Mr. Lee has been pressing hard for this assurance of protection in the face of escalating North Korean threats – and reported signs of North Korean preparations for a third underground nuclear test.
Lee, arriving in Washington on Monday, is expected to place the need for a guarantee of American nuclear defense of the region at the top of an agenda as he meets with Secretary of State Hillary Rodham Clinton and Defense Secretary Robert Gates before seeing Mr. Obama.
South Korea seeking commitment
US and South Korean officials are reported to have already worked out the wording of what is expected to be a joint statement by the two presidents in which they stress the North Korean threat and US capability of deterring nuclear weapons in a showdown.
The statement will not use the term "nuclear umbrella," according to South Korean sources, but will refer to the need for continued "nuclear deterrence." That term, besides covering US nuclear strength, could also include the capability of US destroyers equipped with Aegis-class countermissile systems to shoot down missiles tipped with weapons of mass destruction, whether nuclear, biological, or chemical.
"We expect President Lee and President Obama will agree on how to fortify the nuclear umbrella," says Kim Tae-woo, vice president and senior researcher at the Korea Institute for Defense Analyses. "They have agreed in principle."
That agreement was reached, he says, when South Korea's foreign minister, Yu Myung Hwan, called on Secretary Clinton at the State Department on June 5. In that conversation, Mr. Yu pressed for the sanctions imposed on North Korea by the United Nations Security Council last Friday and also focused on guarantees of US defense.
"Ordinary South Koreans want a binding document on the US providing a nuclear umbrella," says Mr. Kim, reflecting concerns in Seoul that the US is not ready to defend the South while bogged down in wars in Iraq and Afghanistan.
Talk of 'umbrella' prompts storm from North
A written US commitment to maintain a nuclear umbrella over the region will mark a clear escalation of the rhetoric that has flared up in recent weeks in statements from North and South Korea as well as the US.
The US has guaranteed South Korea's defense ever since the end of World War II when the Korean peninsula was divided between North and South. US troops defended the South in the Korean War after the North Korean invasion of June 1950 and the US still keeps 28,500 troops posted in the country.
South Korean officials have been shaken, however, by US insistence on fulfilling an agreement for transferring operational command of all forces in South Korea to a South Korean commander by 2012 in the event of war. They also have questioned why the US has decreased the number of US troops from the 37,000 stationed there several years ago – and more than 50,000 30 years ago.
The prospect of US affirmation of South Korea's nuclear defense by the US has already drawn an outraged response from North Korea. The Workers' Party newspaper Rodong Sinmun, in language laden with somewhat more vitriol than usual, called such a pledge "an unforgivable act" and warned that South Korea would become "a nuclear powder keg that can explode at any moment."
The newspaper, considered to be North Korea's most authoritative state organ, says the pledge would "drive the peninsula into a US nuclear battlefield by drawing more US nuclear weapons into South Korea."
US officials say they removed their nuclear warheads from South Korea around 1990, before South and North Korea signed an agreement for a "nuclear-free" Korean peninsula. But North Korean rhetoric on the topic is assumed to refer to US nuclear strength in the western Pacific, including warheads on Navy vessels that enter South Korean waters during military exercises, as well as US bases in Japan, Guam, and Hawaii.
Trade on agenda
Although the North Korean issue will dominate the Obama-Lee summit, they also are expected to discuss the Korean-US free-trade agreement, reached two years ago after lengthy negotiations. Obama and Clinton, while senators, both criticized the agreement for failing to guarantee a sharp increase in motor vehicle exports to South Korea while assuring ever more imports of South Korean vehicles into the US.