Best summary of the U.S.-North Korea summit by Evans Revere:

"Given how much the North Koreans detest exercises that are intended to demonstrate the US-ROK capacity to “decapitate” the North Korean leadership and overthrow the Kim regime, his surprising commitment is the most strategically significant confidence-building measure (CBM) that could be made, especially since it was offered unilaterally and outside the formal talks with the North Koreans. In effect, the president’s statement also reciprocates the North’s earlier stoppage of missile and nuclear tests—a CBM tit-for-tat."

William R. McKinney Ending US-ROK Military Exercises: An Idea Whose Time Has Come

https://www.38north.org/2018/06/wmckinney061318/