Trump says summit with Kim to take place in Hanoi

US President Donald Trump and North Korean leader Kim Jong Un will meet for a second much-anticipated summit in Hanoi, as preparations kick into high gear for the peace talks.

Trump announced the exact location on Twitter -- only the country, Vietnam, was previously known -- for the follow-on to the leaders' summit in Singapore last year as he hailed "very productive" preparatory talks between diplomats from the two countries.

"My representatives have just left North Korea after a very productive meeting and an agreed upon time and date for the second Summit with Kim Jong Un," Trump said.

"It will take place in Hanoi, Vietnam, on February 27 & 28. I look forward to seeing Chairman Kim & advancing the cause of peace!"

The US State Department said the special US envoy for North Korea will meet again with Pyongyang officials ahead of the Trump-Kim talks -- hours after he returned to Seoul from talks in the North on the summit's agenda.

In a statement, the State Department said talks during Stephen Biegun's three-day trip explored Trump and Kim's "commitments of complete denuclearization, transforming US-DPRK relations and building a lasting peace on the Korean Peninsula."

Biegun landed at Osan US Air Base late Friday, foreign ministry spokesman Noh Kyu-duk told AFP.

The State Department confirmed Biegun agreed to meet his North Korean counterpart Kim Hyok Chol again before the leaders' talks.

North Korea has yet to provide any official confirmation of the summit and Kim Jong Un appeared to make no mention of it during a meeting earlier with the top brass of the Korean People's Army.

As reported by state media, the meeting focused on the need to modernize the military while maintaining party discipline in the ranks.

Biegun is expected to share details of his Pyongyang meetings with his South Korean counterpart Lee Do-hoon and Foreign Minister Kang Kyung-wha on Saturday.

Attention will focus on whether the US team have offered to lift some economic sanctions in return for Pyongyang taking concrete steps toward denuclearization.

Discussions on declaring an end to the 1950-53 Korean War could also have been on the table, with Biegun last week saying Trump was "ready to end this war."

The three-year conflict ended in an armistice, not a peace treaty, leaving the two Koreas still technically at war, with the US keeping 28,500 troops in the South.

The US envoy was also likely to have discussed with his counterpart protocol and security matters for the upcoming Trump-Kim summit.

At their landmark summit in Singapore last year, the mercurial US and North Korean leaders produced a vaguely worded document in which Kim pledged to work towards "the denuclearization of the Korean peninsula."

But progress has since stalled, with the two sides disagreeing over what that means.

Experts say tangible progress on Pyongyang's nuclear weapons will be needed for the second summit if it is to avoid being dismissed as "reality TV."