The U.S envoy for North Korea is in Pyongyang for talks, paving the way for a second leadership summit.
Mr Biegun arrived just as US President Donald Trump confirmed he would meet North Korea’s Kim Jong-un in Vietnam on 27 February.
The two leaders will build on the vague denuclearisation commitments they made when they met in Singapore last June.
Meanwhile, the UN has warned that North Korea is continuing its nuclear programme and breaking sanctions.
The report said actions including the illegal transfer of banned goods at sea could make sanctions the international community’s main way of putting pressure on North Korea ineffective.
The Singapore summit generated significant coverage and optimism, but delivered very few concrete developments.
Both sides said they were committed to denuclearisation, but with no details of how this would be carried out or verified.
Experts caution that despite Mr Trump’s declaration that North Korea is no longer a nuclear threat, the country has never said it would give up its nuclear weapons programme without similar concessions from the US.
Mr Biegun is travelling to Pyongyang after holding talks with officials in South Korea, and has said he wants to achieve some concrete deliverables.
The US state department has said his visit will advance further progress on the commitments the president and Chairman Kim made in Singapore.
The US wants North Korea to make a full declaration of all its nuclear weapons facilities and commit to destroying them, under international supervision something North Korea has never said it will do.
In a speech at Stamford University last week, Mr Biegun said the US would not agree to lift sanctions until this happens, but he indicated it could provide assistance in other ways, saying: We did not say we will not do anything until you do everything.
He also said Kim Jong-un had previously committed to the dismantlement and destruction of all North Korea’s plutonium and uranium facilities, which provide the material for nuclear weapons.
But a report to the UN Security Council on Monday suggested North Korea was continuing its nuclear and missiles programmes, while making efforts to protect its facilities from possible future strike.
The confidential report, a copy of which was seen by news agencies, also said North Korea was routinely breaking international sanctions.
The report said there had been a massive increase in illegal ship-to-ship transfers of petroleum products and coal where material is moved from non-North Korean ships out at sea to evade monitoring.
The international sanctions against North Korea are designed to severely limit its import and export abilities, with the aim of putting pressure on the country to give up its nuclear ambitions.
Source: Voice of Nigeria