When it comes to foreign policy, President Donald Trump has often said he wants to be “unpredictable” and “not reveal his intentions.”

This week, he broke that rule by telling the world exactly what he would do if North Korea continues to threaten the United States. He pledged “fire and fury like the world has never seen.” Soon after that threat, North Korea said it was “examining the operational plan for making an enveloping fire at the areas around Guam.” Guam is a U.S. territory, that is a threat, and there was no “fire and fury.”

Trump said last spring that it took Chinese President Xi Jinping “10 minutes” to convince him that solving problems with North Korea is “not so easy,” and that “Korea was once a part of China.” He has since learned that solving the North Korea problem is complex. I hope he also has learned that Korea was not a part of China. It was once controlled by Japan and after World War II, the United States and Soviet Union divided the peninsula along the 38th parallel, which explains why the Koreas are ideologically opposite.

In 1953, while serving in the Army with the military government unit, I played a small role in the armistice negotiations at Panmunjom. For two years, we struggled with issues from prisoner exchanges to establishing a Demilitarized Zone. Mao Zedong in China and Josef Stalin in Russia were pulling the intransigent North Korean strings. Although China did not want a war on its borders, it also did not want a strengthened U.S. presence on the peninsula. It was shortly after Stalin’s death that the deal was closed. The treaty was designed to “insure a complete cessation of hostilities and of all acts of armed force in Korea until a final peaceful settlement is achieved.” It should be noted that South Korea never signed the agreement nor was it in favor of it.

A key provision prohibited the introduction of new weapons into the peninsula, specifically atomic weapons. That provision was broken — not by North Korea, but by the United States. It was President Dwight Eisenhower in 1957 who breached the accord by taking 280 mm atomic cannons into South Korea. A year later, we armed atomic cruise missiles that could reach China and Russia. In 1994, hostilities almost broke out when Kim Jong Un’s father refused to allow international inspectors access to North Korea’s facilities as required under the Nuclear Non-Proliferation Treaty. That conflict was resolved diplomatically when North Korea pledged to denuclearize, but kept its options open to build an actual weapon.

I will not outline the other treaty transgressions and confrontations on the Korean Peninsula, where we lost 37,000 troops in a brutal and nearly forgotten war. But as Secretary of Defense James Mattis said, you must “engage your brain before you engage your weapon.” We must not only know the history of the region, we must examine the motivation of our enemy.

As deranged as Kim appears, he knows what happened to Saddam Hussein and Moammar Gadhafi. And he knows that we are reluctant to execute a regime change if that regime controlled atomic weapons. Kim also knows that we would be reluctant to attack him militarily. To do so would give North Korea an excuse to unleash mayhem on South Korea with conventional weapons, slaughtering millions in Seoul.

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North Korea will develop atomic weapons and intercontinental missiles, and we won’t do a thing but regret past mistakes. Whatever appetite Kim has to wage war will be stifled by China, which does not want an armed conflict on its border or the hordes of refugees a war would generate. Or, Trump might just tweet us into another conflict in the region.

I’m too old to go again, but I fear for my grandchildren.

Sol Wachtler, a former chief judge of New York State who was an Army sergeant during the Korean War, is a distinguished adjunct professor at Touro Law School.