‘We’re turning the page on a decade of war,” President Obama said Thursday as he announced an effective end to America’s ability to secure robustly its many and varied global interests.

Obama’s so-called “Priorities for 21st Century Defense” primarily blunts the pointed end of the security spear by reducing the size of the Army and Marine Corps by up to 15 percent.

No more kinetic power-projection for you, America.

This is not a surprise.

As a candidate for president four years ago, Barack Obama made his priorities clear: Social spending comes first.

That sensibility certainly reflects Washington’s inability to curb its engorged appetite for entitlement spending — Medicaid, Medicare and Social Security, in particular — and there is only so much money to go around now.

Thus, in the president’s view, the need for a far leaner Pentagon.

Try bulimia, the doctor ordered — demanding $487 billion in spending cuts.

Obviously there is much room for belt-tightening in the defense budget. The Pentagon spent 20 years and $62 billion developing the F-22 Raptor, a fighter so stealthy no enemy has ever seen it — not the least reason being that it has never flown a single combat mission, even though it was fully operational during the wars in Iraq, Afghanistan and Libya.

Room for some cuts? Sure enough.

But there is a naive arrogance in the belief that a White House ukase is a meaningful security prescription.

Turning the page on a decade of war?

What if war turns the page back — and America is unprepared?

Again.

It’s been 70 years since Pearl Harbor, which caught America flat-footed. So did Korea and 9/11.

One can never prepare for all eventualities — but neither should one presume that even great nations can control history.

Defense Secretary Leon Panetta promised Thursday that the Army and Marines “will no longer need to be sized to support the kind of large-scale, long-term military operations that have dominated military priorities” for decades.

Really?

How does he know?

Has any thought been given to the fact that a force-in-being, by its very existence, is a stabilizing influence?

And that its sudden removal would only encourage adventurers and zealots — to America’s profound detriment?

As Max Boot wrote in Commentary magazine, “It is beyond bizarre that we are rushing to spend [a] peace dividend at a time when we are not actually at peace.”

Nor is there even the illusion of peace: Iraq already is on the skids. Iran threatens the world’s principal oil source. Instability racks the Middle East. What does the future hold for the Korean peninsula?

Who made this America’s responsibility?

History.

Washington will shirk the burden to the nation’s profound detriment.