“If China is not going to solve North Korea, we will.”

So President Donald Trump warns, amid reports North Korea, in its zeal to build an intercontinental ballistic missile to hit our West Coast, may test another atom bomb.

China shares a border with North Korea. We do not.

Why then is this our problem to “solve”? And why is North Korea building a rocket that can cross the Pacific and strike Seattle or Los Angeles?

Is Kim Jong Un mad?

No. He is targeting us because we have 28,500 troops on his border. If U.S. air, naval, missile and ground forces were not in and around Korea, and if we were not treaty-bound to fight alongside South Korea, there would be no reason for Kim to build rockets to threaten a distant superpower that could reduce his hermit kingdom to ashes.

While immensely beneficial to Seoul, is this U.S. guarantee to fight Korean War II, 64 years after the first wise? Russia, China and Japan retain the freedom to decide whether and how to react, should war break out. Why do we not?

Would it not be better for us if we, too, retained full freedom of action to decide how to respond, should the North attack?

During the August 2008 war between Russia and Georgia, despite John McCain’s channeling Patrick Henry — “We are all Georgians now!” — George W. Bush decided to take a pass on war. When a mob in Kiev overthrew the pro-Russian government, Vladimir Putin secured his Sebastopol naval base by annexing Crimea.

Had Georgia and Ukraine been in NATO, we would have been, in both cases, eyeball to eyeball with a nuclear-armed Russia.

Which brings us to the point:

The United States is in rising danger of being dragged into wars in half a dozen places, because we have committed ourselves to fight for scores of nations with little or no link to vital U.S. interests.

To honor commitments to the Baltic States, we have moved U.S. troops to the Russian border. To prevent China from annexing disputed rocks and reefs in the South and East China Seas, our Navy is prepared to go to war — to back the territorial claims of Tokyo and Manila.

Yet, our richest allies all spend less on defense than we, and all run trade surpluses at America’s expense.

Japan and South Korea are of like mind. Neither spends nearly as much of GDP on defense as the U.S. Yet, we defend both, and both run endless trade surpluses at our expense.

President Trump may hector and threaten our allies that we will not forever put up with this. But we will, because America’s elites live for the great game of global empire.

What would a true “America First” foreign policy look like?

It would restore to the United States the freedom it enjoyed for the 150 years before NATO, to decide when, where and whether we go to war. U.S. allies would be put on notice that, while we are not walking away from the world, we are dissolving all treaty commitments that require us to go to war as soon as the shooting starts.

If Germany, Japan and South Korea are no longer assured we will go to war on their behalf, all three would take a long hard look at their defenses. The result would likely be a strengthening of those defenses.

But if we do not begin to rescind these war guarantees we have handed out since the 1940s, the odds are high that one of them will one day drag us into a great war, after which, if we survive, all these alliances will be dissolved in disillusionment.

What John Foster Dulles called for, over half a century ago, an “agonizing reappraisal” of America’s alliances, is long, long overdue.