President Donald Trump’s much-feted summit with North Korean leader Kim Jong Un ended early and in disappointment on Thursday, when the U.S. delegation announced it could not reach any concrete deal on denuclearization with the authoritarian state. For all Trump’s bombast on North Korea, little material progress has been made in denuclearizing the Korean Peninsula. The president has boasted of his achievements in American-Korean relations, but his self-described successes have all come at a price. Though atomic weapon and ballistic missile tests have stopped, Trump agreed to end joint military exercises with South Korea. And though Trump lauded the diplomatic significance of a sitting U.S. president meeting a North Korean leader for the first time, the June 2018 Singapore summit gave Kim a priceless propaganda win. In the meantime, Pyongyang is reportedly continuing its nuclear research program regardless. The Vietnam summit held this week was designed to build on the mutual commitment of both nations to work toward improved relations and disarmament on the peninsula. But observers were left disappointed when the meeting broke up early . A working lunch was canceled, a joint declaration scrapped and Trump’s press conference moved up several hours. He then told the assembled journalists…