Trump ruled out immediate sanctions relief for North Korea after his meeting with Kim, saying it would come "when we are sure that the nukes are no longer a factor".
Stanford University nuclear scientist Siegfried Hecker told the New York Times last month that the nuclear disarmament of North Korea could take 15 years, and that the best the United States can hope for is a phased process that goes after the most risky parts of the North's weapons program first.
As he said, it is the first study to highlight how risky it is and how much boomerang the use of nuclear power can turn to the country that uses it, especially because of the environmental impact that will spread worldwide.
A task force has been also launched to prepare for possible tour programmes in the North by South Korean tourists, according to the Korea Tourism Organisation.
Reseachers hold a forum at the private think tank Sejong Institute in Seongnam, just south of Seoul, on June 14, 2018, to analyze the outcome of the June 12 summit between U.S. President Donald Trump and North Korean leader Kim Jong-un.More news: Putin hails outcome of Trump’s meeting with North Korean leader
In the 1990s North Korea had not yet developed nuclear weapons.
Nor were there any USA concessions on sanctions relief, normalisation of relations absent progress in human rights or a more extensive security guarantee to the regime than previously provided, he said.
During a press conference after the summit, Trump said that both U.S. experts and global organizations would carry out the verification of the North Korean denuclearization process.
The Federation of American Scientists (FAS) estimates there are roughy 14,500 nuclear weapons around the globe as of early 2018, most of which are owned by the U.S. and Russia.
Last year, as North Korea carried out further nuclear weapons and ballistic missile tests, since conducting its first nuclear test in 2006, the UN Security Council adopted several resolutions condemning the launches and toughening sanctions against DPRK.
Seven Democratic Party hawks, including Senate Minority Leader Chuck Shumer and Senator Dianne Feinstein, indicated they would vote against any agreement unless the DPRK eliminates all nuclear and biological weapons, dismantles all ballistic missiles, and allows intrusive inspections anywhere in the country. "But we may never get to the endpoint". Verifying denuclearisation in North Korea would be achieved "by having a lot of people there", he said.