U.S. President Donald Trump (L) speaks at a press conference in Hanoi, Vietnam, Feb. 28, 2019. A gap remained between what the Democratic People's Republic of Korea (DPRK) wanted and what the U.S. wanted, Donald Trump told the press conference, explaining the earlier-than-scheduled end to his second summit with DPRK top leader Kim Jong Un. (Xinhua/Wang Shen)