As the year comes to a close, and as President Trump’s foreign policy suddenly veers in the wrong direction with wild and ill-advised moves on Syria and Afghanistan, here’s a national-security columnist’s wish list for 2019.

Foremost, the president must return to the instincts that convinced hawks like Mr. Trump’s golfing buddy Lindsey Graham, and many other GOP foreign-policy types, that he is up to the job and capable of doing good in the world.

Mr. Trump’s allies as well as his constant critics panned the Syria decision. All pointed to a line in Secretary of Defense Mattis’ resignation letter that urged “treating allies with respect and also being clear-eyed about both malign actors and strategic competitors.”

Yet it was President Trump who imposed new sanctions on malign actor Iran. It was Mr. Trump who authorized the sale of arms to our ally Ukraine — to the chagrin of one strategic competitor, Russia. It was Mr. Trump who (for better or worse) launched a tariff war against another rival, China.

Mr. Trump also moved the American embassy to Jerusalem, pleasing America’s closest ally, Israel, and bonded with the president of our strongest ally in the Pacific region, Shinzo Abe of Japan. Finally, it was Mr. Trump who punished the Syrian regime’s chemical atrocities with an airstrike (though he should have followed up).

True, relations with Europe’s ­ever-moralizing leaders chilled, but that alliance didn’t collapse, ­either. Meanwhile in this hemisphere, a rebranded NAFTA diffused tensions, and now Mr. Trump has a new ally in Brazil, a key South American player.

Alas, the decision to betray Kurds, Muslims, and Christians who fought against ISIS alongside us has marred that promising start. Israeli defense officials are quietly seething. The winner is Turkish strongman Recep Erdogan, who is in cahoots with Russia, Iran, and Sunni extremists, and is cultivating regional anti-Americanism. Now Turkey is ready to smash our anti-ISIS allies.

Let’s hope, as Mr. Trump revamps his national-security team, for quiet tweaks to the Syria decision (walking it back fully would be uncharacteristic). The goal: Reassure Kurds, help Israel intensify its campaign against Iranian entrenchment on its borders, and forestall an ISIS resurgence.

President Trump’s decisions to pull out may have its reasons, but if so, in 2019 he must better explain them to Americans. Why, for example, cut American troops in Afghanistan by half with the aim of ending all involvement there? Why an immediate redeployment, rather than conditioning the announcements on significant progress?

Trumpians warn of “endless wars,” but today’s military campaigns can’t end in clear victories and perhaps they aren’t supposed to. They are more akin to lawn-mowing, uprooting global bad weeds on a regular basis. Remember: No mandatory draft or national mobilization is needed. Instead, these wars ­require patient, continuous attention with relatively small footprints.

A few other wishes:

• Intensify the arming of Ukraine and convince Europeans to buy American, rather than Russian, energy. Do these things first, before any attempt to warm relations with Moscow.

• Apply more economic pressure on Beijing. The Chinese need us economically more than we need them. Also, show naval strength in the South and East China seas.

• Pressure Saudi Crown Prince Mohammed bin Salman to deepen domestic reforms, make his Israel ties public, wind down the Yemen war and, crucially, end his destructive feud with Qatar.

• Stay the course on Iran. Avoid seeking a deal that would only strengthen the clerical regime’s tenuous hold on power. Likewise, avoid any North Korea deal that would benefit the Kim regime while endangering Asian friends.

• For now, forget about an Israeli-Palestinian “deal of the century.” Israel just set an April election, and any move would be futile prior to the end of Mahmoud Abbas’ four-year term, which, curiously, started 14 years ago.

• By all means, further beef up military budgets while fine-tuning the force for 21st-century battlefields. Avoid signaling that you would never use that military might.

• America is the indispensable force for good in the world. Without our active engagement, the world is worse off, as are we. Here’s hoping that in 2019 President Trump makes America first again among global powers.