South Korean President Moon Jae-in and North Korean leader Kim Jong Un attend the inter-Korean summit at the truce village of Panmunjom, in this still frame taken from video, South Korea, April 27, 2018.

Missile testing

This first inter-Korean summit in over a decade marks a dramatic turn toward diplomacy to resolve the growing North Korean nuclear threat, after a two-year period of continuous North Korean nuclear and missile tests.

Kim has suspended further tests and declared in November that North Korea achieved its goal of developing the capability to target the U.S. mainland with intercontinental ballistic missiles (ICBM).

The U.S., however, argues that further testing is needed to demonstrate operational ICBM capability. Also in the last year, Trump's maximum-pressure campaign led to international efforts to impose tough sanctions restricting most North Korean exports, which may have forced Kim to pursue talks to seek sanctions relief.

Recently, North Korea announced it would close its Punggye-ri nuclear test site but analysts are skeptical that these measures would lead to any permanent reduction in the country's nuclear capabilities.