Now that North Korean leader Kim Jong Un has pledged to work toward the denuclearization of the Korean Peninsula, the focus will turn to Pyongyang's willingness to actually dismantle its nuclear weapons program under robust international verification.
Verification, analysts say, is key in achieving the "complete" denuclearization Kim promised during a historic meeting Tuesday with U.S. President Donald Trump in Singapore.
A joint statement issued after the first-ever U.S.-North Korea summit makes no reference to verification nor to a time frame to achieve denuclearization. But Trump said Tuesday a denuclearization process "will be verified" and that senior officials from the two sides will work out details.
Analysts say whether North Korea will allow inspectors from a verification organization such as the International Atomic Energy Agency into the country will be the first major test for Kim's promise to rid Pyongyang of nuclear weapons, including an estimated up to 60 warheads.
Allowing IAEA inspectors to the North's main Yongbyon nuclear complex, as well as unfettered access to other facilities and the only known nuclear test site in Punggye-ri, will be crucial for conducting credible verification activities.
"There will be many tests along the way in this process. But for me, the first major test will be if the North Koreans agree to let the IAEA or another multilateral combination of inspectors come in," said Suzanne DiMaggio, a senior fellow at New America, a U.S. research group.
The U.N. nuclear watchdog has not had access to North Korean nuclear facilities since its personnel were expelled in 2009. Recently, Japan has offered to cover the initial costs of IAEA inspections if North Korea agrees to resume them.
U.S. officials say they have been repeatedly cheated by North Korea in previous negotiations on denuclearization. A bilateral deal in 1994 collapsed when Washington accused Pyongyang of secretly enriching uranium, while a six-nation agreement in 2005 fell apart in a dispute over how to verify a nuclear freeze by the North.
"The key thing is that whatever we do, we start with verification," said Corey Hinderstein, vice president of international fuel cycle strategies at the Nuclear Threat Initiative in Washington.
Such verification would include a declaration by North Korea of its nuclear weapons, related facilities and fissile materials to a verification organization like the IAEA.
While reviewing the declaration and verifying the dismantlement, the Vienna-based agency would continue its inspection activities to ensure against undeclared nuclear activities and reach a conclusion about the completeness of the North's declaration.
(Punggye-ri nuclear test site)
[DigitalGlobe/38 North via Getty/Kyodo]
Hinderstein stressed the importance of the United States, the IAEA and other parties addressing Pyongyang's nuclear capability comprehensively to include fissile material production -- both uranium and plutonium -- and weapons-building infrastructure.
"Even if we cut something off today, if you have a robust research and development program or production infrastructure, you may have cut off the head but the chicken's still running around," she said.
As part of the process to achieve the "complete" denuclearization, David Albright, president of the Institute for Science and International Security in Washington, referred to the possibility of moving North Korean nuclear scientists and engineers to other countries including the United States.
Foreign governments and organizations should create opportunities for them to work in the fields of civil nuclear power and renewable energy, Albright said.
Experts argue it would take years to conduct verification activities, especially in a country like North Korea with relatively advanced nuclear weapons and ballistic missile programs.
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 dangerous parts of the North's weapons program first.
"So we're not going to have a definitive answer to 'Do we get fooled again?' either until North Korea once again defects from the process or until it becomes clear that they are refusing to reopen or resume it," said Scott Snyder, senior fellow for Korea studies at the Council on Foreign Relations, a U.S. think tank.
"My guess is that they would reopen it and come into a negotiated process again, but they may do this as a way of buying time," Snyder said. "But we may never get to the endpoint."
Albright advised that the Trump administration and the U.N. Security Council should not remove sanctions against North Korea early, saying they are the "leverage" in compelling the country to take concrete measures toward denuclearization.