While Kim Jong Un and President Donald Trump have taken a break from exchanging bellicose threats, new developments in Korea and China underscore why the crisis has not been averted — merely postponed.

An update from Foreign Policy’s daily newsletter relates a couple of important developments:

Talking with Beijing. President Trump and the North Korean regime of Kim Jong Un have scaled back the rhetoric in recent days, after a week of sparring over North Korea’s missile and nuclear programs that had many fearing the two countries were stumbling toward military conflict.
But things remain dicey. Gen. Joseph Dunford, the chairman of the Joint Chiefs has spent the last several days in China meeting with military and political leaders, and on Wednesday, will make what the WSJ says is a rare visit “to the Chinese armed-forces command that oversees the territory bordering North Korea, a move experts say suggests Beijing’s displeasure with Pyongyang.”
Dunford and his counterpart, Gen. Fang Fenghui signed an agreement aimed at improving communication between the their military forces that will “reduce the risk of miscalculation” in the region, according to a Pentagon statement.
Muscle flexing. Tensions have cooled, but are hardly gone. In the coming days, thousands of U.S. and South Korean forces will conduct an annual war game guaranteed to anger the North, which sees such demonstrations as a provocation.
Elsewhere, two U.S. Air Force B-1B bombers from Andersen Air Force Base on Guam and two Japanese F-15 jet fighters conducted drills southwest of the Korean peninsula on Wednesday. “These training flights with Japan demonstrate the solidarity and resolve we share with our allies to preserve peace and security in the Indo-Asia-Pacific,” the U.S. Air Force said in a statement.
But in a sign of the times, South Korean President Moon Jae-in on Tuesday said his country can no longer rely on Washington for protection.[1]

To clarify the last statement, Moon was emphasizing that South Korea has to do more itself to provide security for its people. He was not questioning the trustworthiness of the U.S.
Okay, so what comes next? North Korea will continue to develop its warheads and its missile delivery systems until someone stops them (China or the U.S.)  Can the U.S. and its allies afford to let the development process continue unabated? Could it lead to a provocation engineered by the U.S. (a false flag), to force a conflict in which the U.S. could feel justified for taking massive military action against North Korea? It is very possible.  However, it is more likely that Kim continues to fire missiles pell-mell into the Pacific.  Consequently, détente isn’t going to happen.  Pyongyang will either force the issue, or the U.S. will — even if the triggering event is contrived like the Gulf of Tompkin affair [2].
 If the sanctions pressed by nations who trade with North Korea fail to stop North Korean weapon development programs, the Pacific allies (the U.S., South Korea, and Japan) won’t sit around indefinitely, blithely allowing substantial progress by Pyongyang in nuclear weaponry and delivery systems. A casus belli still looms large. North Korea won’t forsake its weapons program which it sees as essential to its survival.  Therefore, we should not expect the “triggering event” to languish much longer.

[1] Paul McLeary, Situation Report, Foreign Policy,August 16, 2017.
[2] From Wikipedia:  “The Gulf of Tonkin incident (Vietnamese: Sự kiện Vịnh Bắc Bộ), also known as the USS Maddox incident, drew the United States (U.S.) more directly into the Vietnam War. It involved two separate confrontations involving North Vietnam and the United States in the waters of the Gulf of Tonkin.”  Most pundits today emphasize that the incident was a false flag to justify the Viet Nam War.
The Casus Belli of the Vietnam War