Philippines President Rodrigo Duterte has just given us notice he will be terminating the Visiting Forces Agreement that governs U.S. military personnel in the islands.

His notification starts the clock running on a six-month deadline. If no new agreement is negotiated, the VFA is dissolved.

What triggered the decision?

Duterte was offended that one of his political allies who led his anti-drug campaign in the islands, which involves extrajudicial killings of drug dealers, had been denied a U.S. visa.

Yet, Duterte has never been an enthusiast of the U.S. presence. In 2016, he told his Chinese hosts in Beijing: “I want, maybe in the next two years, my country free of the presence of foreign military troops. I want them out.”

The Pentagon is shaken. If there is no VFA, how do we continue to move forces in and out to guarantee our ability to honor the 1951 Mutual Defense Treaty? Defense Secretary Mark Esper called Duterte’s action “a step in the wrong direction.”

President Donald Trump openly disagreed: “If they would like to do that, that’s fine. We’ll save a lot of money.”

The Philippine Islands are among the largest recipients of foreign aid in East Asia, and we’ve provided $1.3 billion in military assistance over the last two decades. But money shouldn’t be the largest consideration here.

Trump has been given a historic opportunity to reshape U.S. and Asia policy along the lines he ran on in 2016.

He should tell Duterte that we accept his decision and that we, too, are giving notice of our decision to let the 1951 treaty lapse. And following expiration of that treaty, the U.S. will be absolved of any legal obligation to come to the defense of the Philippines.

Time for Manila to take charge of its own defense. Indeed, what is the argument for a treaty that virtually dictates U.S. involvement in any future war in 7,600 islands 8,000 miles from the United States?

When we negotiated the 1951 treaty, it was a different world.

We had entered a Cold War with Stalin’s USSR. We were in a hot war in Korea that would cost 37,000 U.S. lives. Gen. Douglas MacArthur had just been relieved of his command of U.S. forces in Korea by Harry Truman. A disarmed Japan had not fully recovered from World War II.

The Communist armies of Chairman Mao had overrun China and driven our Nationalist allies off the mainland. The Viet Minh were five years into a guerrilla war to drive the French out of Indochina.

Today, the Cold War is long over. Vladimir Putin’s Russia is no threat to the Philippines. Nor is China, though Xi Jinping has occupied and fortified islets like Mischief Reef in the South China Sea that are within the exclusive economic zone of the Philippines.

There is no U.S. vital interest at risk in these islands to justify an eternal war guarantee or treaty commitment to fight Beijing over rocks and reefs in the South China Sea.

Trump should seize this opportunity to tell Duterte that when the VFA, which guarantees immunity for U.S. forces in the Philippines, is dissolved, the 1951 Mutual Defense Treaty is dissolved.

A message would be sent to Asia, and the world, that Trump was serious when he said that he intends to revisit and review all the defense alliances and war guarantees entered into 60 and 70 years ago, to address threats that no longer exist in a world that no longer exists.

The U.S. has a long history with the Philippines, beginning in the War of 1898 with Spain, when Admiral George’s Dewey’s Asian squadron sank a Spanish fleet in Manila harbor, and we invaded, occupied and colonized the islands, thus emulating Europe’s imperial powers and abandoning the anti-colonial legacy of the Founding Fathers.

“Take up the White Man’s burden,” Rudyard Kipling admonished us.

After Filipino patriots fought for nearly four years to liberate their islands from the Americans, as they had from the Spanish, inflicting on U.S. soldiers and Marines thousands of casualties, the New York Herald replied to the Poet of Empire:

“We’ve taken up the white man’s burden/Of ebony and brown/Now, will you tell, Rudyard/How we may put it down.”

After Pearl Harbor in December 1941, the Japanese invaded and occupied the islands, until Gen. MacArthur made good in on his famous pledge on leaving Corregidor, “I shall return.”

In 1944, we liberated the islands.

A year after Japan’s surrender, on July 4, 1946, we granted the Philippines full independence. And that nation and people, far more populous and prosperous than in 1946, should take full custody of the defense of their own sovereignty and independence.

At the end of the Cold War, nationalists in Manila ordered the U.S. to vacate the great naval base we had built at Subic Bay. We should have used that expulsion to let the 1951 security treaty lapse.

Trump should not miss this opportunity.

(Patrick J. Buchanan is the author of “Nixon’s White House Wars: The Battles That Made and Broke a President and Divided America Forever.”)