SEOUL • The surprising announcement that US President Donald Trump and North Korean leader Kim Jong Un will hold an unprecedented meeting by May is the latest and most astonishing step forward in a flurry of diplomacy.
The two and their respective allies fought each other to a ceasefire in the 1950-1953 Korean War, and Pyongyang has, for decades, defied heavy sanctions to pursue its nuclear weapons and ballistic missile programmes, developing rockets that can reach the US mainland.
However, it has offered to put them on the negotiating table if what it calls threats against its regime are eliminated.
But where will the historic summit be held?
"Does this mean Chairman Kim is coming to Washington or does it mean the President of the United States is going to travel to North Korea?" asked Dr Jim Walsh, a senior research associate at the Massachusetts Institute of Technology's security studies programme, according to The Guardian.
If it happens in Pyongyang, Mr Kim is sure to put on a spectacular show for his visitor, but for America, it would run the risk of appearing that Mr Trump is going to pay his respects.
The Demilitarised Zone that divides the two Koreas - where Mr Kim and South Korean President Moon Jae In are to meet late next month - is probably the favourite at this stage, offering ease of access for both sides, a controlled environment and facilities already in place.
It would also appeal to the two men's sense of drama.
A more neutral location with less weight of symbolism such as Beijing or Geneva - Mr Kim was educated in Switzerland - would mean that the key players would have to plan events with another host country.
Furthermore, it would involve a journey on both sides, and Mr Kim has not left the North since inheriting power from his father in 2011.
But some experts say China is not a likely option.
Mr Christopher Hill, a former US ambassador to North Korea, told America's MSNBC network that it "wouldn't be China because I think the North Koreans want to show they can deal with the US and not through China".
Seoul would most likely be unthinkable to Pyongyang, and Washington even more so, but on the other hand, no one would have predicted three months ago that Mr Kim's sister would visit the South Korean capital within weeks.
The United Nations headquarters in New York - Mr Trump's home town - would mean Mr Kim stepping on American soil, but the UN has a long history of hosting a rogues' gallery of wo-rld leaders.
A long shot is Mr Trump's Mar-a-Lago estate in Florida, where he has entertained world leaders, including China's President Xi Jinping, suggested The Guardian.