SEOUL, South Korea – At the heart of the nuclear impasse with North Korea is a seemingly straightforward demand by both North and South for a formal end to the Korean War.
It appears reasonable, on its face.
While there's been occasional, sometimes serious violence since the war ended in 1953, including in 2010 when 50 South Koreans were killed in attacks blamed on the North, the enmity hasn't risen to full-scale fighting since.
But war remains. That's because the Korean War ended with a military cease-fire, in the form of an armistice, not a formal peace treaty.
Figuring out how to make a peace agreement will be a critical part of the summit now taking place between South Korean President Moon Jae-in and North Korean leader Kim Jong Un.
Washington's current reluctance to move ahead on the Koreas' call to formally end the war highlights just how big a concession many observers feel it would be.
There are worries that it would remove key leverage against North Korea and might make war more, not less, likely, if it creates momentum toward withdrawing the U.S. troops stationed in South Korea as a buffer against North Korean aggression and, if Pyongyang gets its way, inserts a wedge between Seoul and its U.S. ally.
There have been calls for a peace treaty, a peace regime and an end-of-war declaration. But what does each mean? What nuclear moves will North Korea have to make to satisfy Washington? And what part will U.S. President Donald Trump play?
AP takes a look:
WHAT KIND OF PEACE?
The general idea, from the Korean side, is to get an end-of-war declaration this year that would then begin a process to replace the 65-year-old armistice with a formal peace treaty.
If that end-of-war declaration is settled — no easy task — years of legal and political negotiations to get to a peace treaty would lie ahead.
In the meantime, if like-minded, liberal governments remain in power in Seoul, supporters would try to set up a "peace regime" that could see increased trade, deeper engagement and incremental disarmament — all meant to make sure that peace holds.
WHY THERE'S WORRY
Washington has so far said that there can be no end-of-war declaration until North Korea reveals the contents of its nuclear program as a precursor to dismantlement. North Korea is calling for the peace declaration to come first.
The United States fears that doing it North Korea's way would remove its leverage and allow the North to endlessly draw out the process by providing only partial nuclear concessions as it reaps rewards.
There's also worry that a legally binding peace treaty would allow North Korea, and its backers in the U.N. Security Council, Russia and China, to demand that the U.S.-controlled U.N. Command that polices the Korean border under the armistice be disbanded.
"Kim Jong Un's demand for a treaty is not a genuine call for peace, but rather an effort to erode the strong South Korean-U.S. position that has prevented war for 65 years," David Maxwell, a senior fellow at the Foundation for Defense of Democracies, wrote last month. "Pyongyang believes the departure of U.S. forces from South Korea would allow (Kim) to coerce the South and, if necessary, apply force to achieve his objectives without U.S. interference."
South Korean officials who visited Pyongyang earlier this month said Kim Jong Un told them that an end-of-war declaration wouldn't weaken the U.S.-South Korean alliance or lead to the withdrawal of the 28,500 U.S. troops stationed in South Korea.
But Kim has yet to make any of his assurances in public, and his propaganda services have not released a detailed proposal for what the North wants an end-of-war declaration to look like.
Moon Chung-in, a special national security adviser to President Moon, has said that Seoul would try to make sure that any peace deal retains the existing armistice agreement until a treaty is signed, and would also try to include an item that links the denuclearization of North Korea with a peace regime on the Korean Peninsula.
But Thae Yong Ho, a former North Korean diplomat who defected to the South in 2016, warned on his blog last week that North Korea has consistently maintained until now that an end-of-war declaration would put an end to the armistice and dissolve the U.N. Command.
CAN A DEAL HAPPEN?
Standing in the way of a peace treaty are both Koreas' constitutions, which would have to be changed because each claims sovereignty over the entire Korean Peninsula.
This could be difficult in South Korea, where many conservatives are deeply skeptical of North Korea's intentions and Moon's attempts to engage the North.
"On the North's side, it would be a useful test of Pyongyang's sincerity to ask it to officially give up its claim to sovereignty over the South in the declaration," said Ralph Cossa, an Asia expert at the Pacific Forum.
Both Koreas likely have an ally in Beijing, which has long been wary of the U.S.-South Korean alliance and the presence in the South of U.S. troops and their high-tech, high-powered technology and weapons.
Even if U.S. forces remain in the South after a peace deal, the removal of the U.N. Command would end an agreement with Tokyo that calls for military bases in Japan to assist in the defense of the South, Cossa said. Getting all U.S. troops out of Northeast Asia is a longtime goal of North Korea.
The U.S. Senate would be another big hurdle. Confirmation of a treaty requires a two-thirds vote, which, Cossa points out, would be a tough sell if North Korea is still armed with nuclear missiles.
Asked about the U.S. position on a war-ending declaration, a State Department spokesperson, who requested anonymity because they were not authorized to comment by name, said that during their June summit in Singapore, "President Trump and Chairman Kim committed to working toward complete denuclearization and to joining their efforts to build a lasting and stable peace regime on the Korean Peninsula. Efforts toward a lasting peace regime are dependent on progress toward complete denuclearization."
Trump, ahead of that June summit, acknowledged that he talked with a visiting North Korean envoy about ending the war. "It's got to be the longest war — almost 70 years, right? And there is a possibility of something like that. ... Can you believe that we're talking about the ending of the Korean War?"
But Trump has also reportedly expressed deep skepticism of the U.S. military presence in South Korea.
An end-of-war declaration, Cossa said, could be taken by Trump as "further justification to follow this instinct, which in my view would be destabilizing and would lead to a great push (at least among the defense community in South Korea) for development of an independent South Korean nuclear capability."
Associated Press writers Kim Tong-hyung in Seoul and Matthew Pennington in Washington contributed to this report.
Foster Klug, AP's bureau chief for South Korea, has covered the Koreas since 2005. Follow him at www.twitter.com/apklug