Throughout the Trump administration, the State Department has repeatedly called for the "complete, verifiable, and irreversible denuclearization” of North Korea. Heading into Donald Trump and Kim Jong Un's diplomatic negotiations in Singapore, Secretary of State Mike Pompeo reaffirmed this ambition on Monday. The talks will present numerous challenges and potential pitfalls, but perhaps the greatest of all is the question of how the global community can verify that North Korea keeps any promises it might make about its nuclear arsenal.

North Korea is, of course, famously reclusive. For decades, the global community has had minimal visibility and insight into the country. Using tools like satellite imaging, heat sensing, and official releases from the North Korean government itself, analysts have been able to piece together some understanding of the country's nuclear weapons program as it has grown. But these examinations are limited and imperfect, due to the dearth of useful intelligence. To have a real understanding of whether North Korea abides by any commitments it makes, the international community would need drastically more transparency and access than it has ever received previously from the Hermit Kingdom.

Camouflage, Concealment, Deception

Experts caution that disarmament is an unlikely outcome of this specific meeting. But any nuclear abatement on North Korea's part, whether it comes now or later, will be incredibly difficult to monitor.

"North Korea does things in such a way where they build critical components of critical facilities in dispersed parts of the country and also underground," says Joseph Bermudez, a strategic advisor of AllSource Analysis, Inc., who analyzes satellite images of North Korea for watchdog group 38 North. "Identifying those facilities and determining what’s in them is extremely difficult, because North Korea since the mid-1960s has practiced what we call CCD—camouflage, concealment, and deception—where you seek to give your opponent a false impression or false understanding of what’s actually happening."

Kim Jong Un said in April that North Korea would pause nuclear weapons testing and even dismantle some of its program facilities. But just that initial gesture has proven difficult to evaluate and verify. The country certainly hasn't conducted any ballistic missile tests since the statement, an event the international community can more easily track because it's, you know, extremely visible. But the question of what exactly North Korea has destroyed and how much it impacts the overall viability of the country's weapons program remains very much open.

Take as an example, North Korea's Punggye-ri Nuclear Test Site, which is housed inside a mountain. Some satellite and seismic data indicates that it recently imploded as a result of increasingly powerful detonations, and has been rendered unusable. But analysts also see some counter-evidence indicating that North Korea simply collapsed the tunnels leading to the facility to make it appear inoperative, while secretly leaving crucial infrastructure intact inside.

'Identifying those facilities and determining what’s in them is extremely difficult.' Joseph Bermudez, AllSource Analysis, Inc.

Punggye-ri is North Korea's main test site, and the country would need to build another in order to continue advancing its bomb technology if the site has actually been destroyed. But the country could conceivably already have another, as yet undetected full-service test site waiting in the wings. And even if it doesn't, recent milestones in the country's hydrogen bomb testing may have left Kim Jong Un confident that North Korean engineers now know how to build adequately light and powerful warheads for ballistic missiles, potentially lessening the immediate need for a test site.

Analysts agree that the only way to confirm whatever nuclear promises North Korea's might make over time would be "an intrusive monitoring and inspection system," as Frank Aum, a former Department of Defense senior advisor on North Korea, puts it. But Aum notes that any successes from the summit would more likely be broad verbal and written commitments, with specific details still months or years away.