So the diplomatic problems are more difficult now than they were in 2000, and will require more creative approaches. Perhaps the biggest diplomatic problem the U.S. will face, if we can get North Korea to agree to fully denuclearize, will be the timing of that denuclearization and how we verify the component steps. These steps will be complex, will take many months, if not years, and will require intrusive verification procedures. But the U.S. has negotiated agreements equally difficult with the Soviet Union, so we do have a positive precedent.

And even before achieving a full denuclearization, effective diplomatic engagement with North Korea could yield valuable interim benefits, including a commitment to stop building and testing new weapons and a reduction in tensions with South Korea.

Indeed, one very important difference this time relative to previous negotiations is the critically important role of the North-South discussions. When I was negotiating with the North almost 20 years ago, I could not get the North to treat South Korea as an equal partner in the negotiations; they treated South Korea as entirely subsidiary to the United States. That has dramatically changed. President Moon has taken bold and intelligent initiatives in reaching out to the North; and they have been reciprocated. President Moon’s initiative could, in time, lead to a normalization between North Korea and South Korea, and that normalization will be critical in building the trust necessary to make any agreement actually work. South Korea should not play a subsidiary role as the negotiations proceed. They are critical to success, and, after all, it is their country that we are negotiating about.