If the U.S. independently destroyed the North Korea infrastructure of nuclear weapons and missiles Kim would need to decide if he would accept that without launching his artillery against Seoul and S. Korea or if he would launch the threatened attack.
Acceptance by Kim would mean he and his regime survive and continue however humiliated and degraded. Launching an attack against Seoul would positively mean the end of Kim and his regime. Kim knows this just as everyone knows this.
U.S. has immense firepower air and naval in any given circumstance as we saw in the air-sea assaults against Iraq in Gulf War I in 1991 and in the three week air-sea-land invasion of Iraq in 2003 (it's what developed afterward that in 2003 was the serious snafu).
With Kim the other day and for the first time threatening to nuke Australia his time with nuclear toys needs to be terminated. Let's hope so. Potus Trump would have bipartisan and nearly unanimous support in the USA to take out Kim's nuclear and missile infrastructure. It's been thought through for 20 years and updated by several administrations in Washington.
Obama's final SecDef the steely hawk Ashton Carter, who knows the Pentagon and U.S. military better than any living person (no less than Bob Gates for sure) has always favored it. Before himself becoming SecDef the nuclear physicist Ashton Carter had served under or formally advised eleven SecsDef.
In 1993, Ashton Carter was placed in charge of the task force on North Korea that issued a position paper for the National Security Council. Carter “wanted military options taken very seriously.” The paper “was very pessimistic about the prospects for negotiations” and recommended launching an attack on North Korea’s nuclear facilities.
One year later, the Clinton Administration was moving toward war, which was now seen as not only likely but desirable. According to Ashton Carter, in 1994 he and [former] Defense Secretary William Perry “readied plans for striking at North Korea’s nuclear facilities and for mobilizing hundreds of thousands of American troops for the war that probably would have followed.” The Yongbyon facility was to be targeted by precision-guided bombs. “We were highly confident that it could be destroyed without causing a meltdown that would release radioactivity into the air.” Carter and Perry felt that the threat posed by North Korea’s nuclear program “was even more dangerous” than military conflict, and they “were prepared to risk a war to stop it.” [2]
Ashton Carter Nomination: Dangerous for the People of Korea | Zoom in Korea