During his first term, President Trump memorably declared that “we more and more are not wanting to be the policemen of the world. We’re spending tremendous amounts of money for decades policing the world, and that shouldn’t be the priority.” His MAGA base may justifiably have thought that America, loaded shotgun in hand, was going to hunker down behind its border wall and tariff barriers during a second Trump term.

It hasn’t worked out that way so far. Instead, Trump is doing what U.S. presidents have done since the end of World War II — policing the world.

In just six months, American diplomats helped to negotiate a peace agreement in the decades-long conflict between the Democratic Republic of the Congo and the Republic of Rwanda, claimed credit for “preventing and ending” a war between India and Pakistan and are trying to broker a ceasefire between Israel and Hamas in Gaza.

Trump ordered a devastating attack on Iran’s nuclear facilities, which even internationalist presidents like Obama and Biden had refrained from doing, and a military operation against the Houthis in Yemen to protect shipping in the Red Sea.

In 2022, then-Senate candidate JD Vance (R-Ohio) staked the isolationist flag by saying, “I don’t really care what happens to Ukraine one way or the other.”

Trump just announced that “we’re sending weapons to Ukraine” in connection to funding from NATO, an organization Trump is suddenly warming to. “It’s not a rip-off,” the president added.

Secretary of Defense Pete Hegseth, suddenly sounding like a Cold War internationalist, reassured America’s Asian allies at a security forum in Singapore that, “No one should doubt America’s commitment to our Indo-Pacific allies and partners.”

And Trump just took his global police role to another level by attempting to modify how a major economic power conducts not its foreign policy, but its internal affairs. He threatened Brazil with 50 percent tariffs unless it dropped criminal charges against far-right former President Jair Bolsonaro over his alleged attempt to overturn the 2022 election.

This isn’t to say that Trump is an effective global policeman or is even acting in the national interest. Iran may still possess the ability to build a nuclear weapon despite Trump’s boast of having caused “complete and total obliteration.” Wars still rage in Gaza and Ukraine, and the Houthis are still sinking ships in the Red Sea.

The Brazil tariffs also defy economic logic — the U.S. runs a trade surplus with Brazil — and appear driven by Trump’s inexhaustible sense of grievance over his own criminal indictments. Meanwhile, your Starbucks order may soon have a surcharge because the chain imports 20 percent of its coffee beans from Brazil.

Nor is there any assurance that this outburst of internationalism is here to stay, because Trump’s policies often have the shelf life of yogurt. Flattery from that foreign leader or a lack of gratitude from this one, and presto — a new policy. If Trump resumes pressure to annex Greenland and the Panama Canal, he’ll look more like a 19th-century imperialist than a 21st-century internationalist.

Can an American president be an effective global leader, whose power depends heavily on building and maintaining alliances, while conducting a tariff war against American allies?

Twice in the previous century America looked inward as successive world wars broke out. Twice it was forced to send millions of U.S. soldiers overseas to fight anyway. Until Trump came along, every president since 1945, Democrat and Republican, recognized that, to quote President John Quincy Adams, while the U.S. should not “go abroad in search of monsters to destroy,” there will always be “monsters” on the prowl for us.

Whether Trump understands that is the question of the day.

Gregory J. Wallance was a federal prosecutor in the Carter and Reagan administrations and a member of the ABSCAM prosecution team, which convicted a U.S. senator and six representatives of bribery. He is the author of “Into Siberia: George Kennan’s Epic Journey Through the Brutal, Frozen Heart of Russia.”