SEOUL, South Korea — North Korean leader Kim Jong Un walked across the border into South Korea early Friday for talks that could mark a historic milestone in one of the world’s most dangerous flashpoints.

Kim entered the southern side of the Demilitarized Zone, the world's most heavily armed border, at 9:30 a.m. local time (8:30 p.m. Thursday ET), where he was due to hold televised discussions with South Korean President Moon Jae-in.

The summit comes after last week's news that President Donald Trump's nominee for secretary of state, Mike Pompeo, recently held one-on-one talks with the reclusive strongman. The Senate voted to confirm Pompeo on Thursday.

With North Korea’s nuclear weapons program having reached what American policymakers describe as a critical stage, expectations are high that the two leaders will lay the foundation for reduced tensions between Pyongyang and Washington.

Among the key issues is the denuclearization of the Korean peninsula. Reaching a mutually acceptable definition of what that means will be central to moving forward with a meeting between Kim and President Donald Trump. It would be the first time a sitting U.S. president has met with a North Korean leader.

It is not clear when any such meeting would take place — American officials have speculated that it could be from late May to mid-June — or where. Singapore, Switzerland, Sweden and Mongolia have all been cited as possible locations.

Friday’s summit was taking place on the South Korean side of the Joint Security Area, neutral ground where North and South Korea hold talks and conduct the limited diplomacy that has existed between them since they signed an armistice here in 1953 halting the Korean War.

The Joint Security Area is the only place where North and South Korean military personnel directly interact, beyond the skirmishes and sometimes serious clashes that have occurred between the two countries in the past.

Diplomatic efforts waned late last year amid Trump’s war of words with Kim. He warned that Kim would be met with “fire and fury”and dubbed him “little rocket man.”

However, earlier this year, South Korea made some breakthroughs with its warring neighbor after a series of meetings and discussions that resulted in North Korea's sending athletes to compete in the Winter Olympics in South Korea. Athletes from the two countries entered the Olympic arena in Pyeongchang under a unified flag, signaling the potential for warmer ties.