Had things gone differently, Victor Cha, 57, could have been on hand to steer Donald Trump’s summit with North Korea on Tuesday.

Last year, the White House nominated Cha as its candidate for ambassador to South Korea. Diplomatic circles overwhelmingly welcomed the news. Cha, a moderate-right foreign policy hawk at Georgetown University, and a former nuclear negotiator with North Korea under the George W. Bush administration, had a reputation as a scholarly, steady hand who could instill sense in the mercurial Trump administration.

But hardliners in the White House and Defense Department had been entertaining talk of a “bloody nose strike” on North Korea—a limited, pre-emptive military attack designed to show the U.S.’s willingness to use force should North Korea continue building nuclear weapons. Cha publicly opposed a strike, writing in The Washington Post about the risk of “a rain of North Korean artillery and missiles” in South Korea.

Over this disagreement, the White House dropped him from his candidacy in January. Then, in a twist starting with South Korean-led diplomacy, Donald Trump agreed in March to meet North Korea’s leader Kim Jong Un, he called off the meeting on May 24, and resumed talks to set up a summit.

Trump will meet Kim Jong Un on June 12 at Singapore’s Capella Hotel, making him the first sitting U.S. president to meet a North Korean leader—and ironically, giving Trump a shot at a historic peace deal, if all goes well.