The historic summit between US President Donald Trump and North Korean leader Kim Jong-un has marked a meaningful step on the long road to peace on the Korean Peninsula.

However, the meeting has left one big question due to the lack of details about how to verify the North’s denuclearization: Is Kim really willing to give up his nuclear weapons?

Liang Tuang Nah, a research fellow of the Military Studies Program at the Institute of Defense and Strategic Studies in Singapore, said that in order to show his sincerity, Kim must allow the International Atomic Energy Agency (IAEA) to inspect key nuclear sites.

“Pyongyang needs to permit unrestricted inspections of its nuclear material production facilities, nuclear storage sites and depots where missiles and warheads are kept,” he said in an interview after the summit.

“These must be conducted by the IAEA along with qualified military experts,” he added.