U.S. President Donald Trump announced May 10 that he and North Korean leader Kim Jong Un will meet in Singapore on June 12. The announcement came shortly after Secretary of State Mike Pompeo's second visit to Pyongyang to meet with Kim and the dramatic return of the three Americans who had been detained in North Korea. Preparation for the first-ever direct meeting between a sitting president of the United States and North Korean leader will no doubt intensify over the next several weeks.

The biggest question about the Trump-Kim summit will be whether the two leaders can reach some kind of an agreement on how to deal with North Korea's nuclear program, and if so, what such an agreement might look like.

For instance, although Kim and South Korean President Moon Jae-in pledged denuclearization of the Korean Peninsula when the two met for the North-South summit on April 27 (and Kim repeated his commitment in a meeting with Chinese Foreign Minister Wang Yi the following week), there is great uncertainty about what Kim means by "denuclearization of the Korean Peninsula."