The Korean War of 1950-53 never formally ended. Fighting was halted by a temporary armistice that remains in effect today, dividing North and South Korea with the world's most heavily armed border. The leaders of South Korea and the United States, however, have said they hope to replace the armistice with a more permanent peace - but experts say that will not happen while Pyongyang builds nuclear arms.
More than half a century after North Korean forces blitzed across the 38th parallel into South Korea, the South's President Roh Moo-hyun wants to put hostilities in the past once and for all.
Mr. Roh and President Bush have said they want to strive for a new peace regime to replace the 1953 armistice that halted the Korean War.
But there are considerable roadblocks to that goal, including decades-old legal issues. The biggest obstacle may be North Korea's nuclear weapon programs. Many experts in Seoul and Washington say that unless the North gives up its nuclear ambitions, there will be no new terms. And, after three years of negotiations, frequently delayed by Pyongyang, there has been no progress on the issue.
Officials in South Korea are careful to use the phrase "peace regime" rather than "peace treaty" when talking about replacing the armistice. Lee Jang-hie, president of the South Korean branch of the International Law Association, says it is difficult to apply a treaty, as it is usually understood under international law, to the Korean War.
"In this war there is no victory state. No defeated state. The character of the Korean war is quite different from a normal war," he noted.
Lee says North Korea has been unwilling to discuss legal topics associated with a treaty - such as war crimes and compensation.
Other legal ambiguities have muddled efforts to replace the 1953 armistice, which only North Korea and the United States signed.
The United States signed on behalf of the United Nations Command - a military coalition of 16 countries. Neither China nor Russia formally acknowledged their participation in the war. South Korea's then-president, Rhee Syngman, refused to back any agreement that left the Korean peninsula divided.
North Korea maintains that only it and the United States can structure the terms of a final peace.
The United States says a deal should, at the very least, include South Korea, and preferably also China and Russia.
Lee supports what he calls a "two plus two" political solution. He says it must begin as a process of building trust between the two Koreas - and only later include other countries.
"We should declare in front of the world and our nation, we have terminated the Korean War. And then this document should be endorsed at least by China and the United States," Lee said.
American lawyer Patrick Norton studied the legal aspects of replacing the armistice for the U.S. State Department. He says the two Koreas first need to find ways to live with each other.
"The important thing is to find a political solution, and not have the political solution dragged around by legal technicalities or old historic issues," Norton said.
The South already is trying to reshape the relationship with its impoverished, Stalinist neighbor, a relationship that for decades after the war was one of hostility.
That changed dramatically in 2000, when former South Korea President Kim Dae-jung held a historic summit in Pyongyang with North Korean leader Kim Jong Il.
South Korea, a democracy and economic powerhouse, has sought to build on the good will of that summit by expanding economic and cultural contacts with the North. Park Chan-bong, a deputy assistant minister at Seoul's Ministry of Unification, says a new North-South relationship is being fostered.
"A more stable, more lasting relationship that is more secure and more peaceful - formed in the process of pursuing unification," he said.
Park says a peace regime will come about when this new North-South relationship matures. However, he warns the relationship will not progress while North Korea maintains its nuclear weapons programs.
"For the countries to talk more about establishing peace on the Korean peninsula, we have to see some progress in terms of the North Korean nuclear resolution," Park said.
The North's weapons programs violate several international pledges it made to not develop nuclear bombs. Five rounds of talks with China, Russia, Japan, South Korea and the United States have done little to persuade North Korea to give up its nuclear ambitions.
That means, many experts say, that no matter what the South Korean officials say and do to improve relations with Pyongyang, there is little chance of a formal change to peace terms any time soon.