President-elect Donald Trump speaks to reporters during a meeting with President Obama in the Oval Office of the White House on Nov. 10. (Michael Reynolds/European Pressphoto Agency)
Deputy Editorial Page Editor

The Trump administration will put an end to the 100 years of U.S. global leadership that began in 1918. It will rend the NATO alliance, cede Eurasia to Russia and the Pacific to China, and adopt as the United States’ best friends populist and authoritarian regimes that despise immigrants and globalization.

Or, after a few early scrapes, its foreign policy will slowly devolve into a somewhat ruder version of President Obama’s. It will bomb terrorists while trying to extract the United States from the Middle East; mix negotiations with Russia and China with pushback against their aggressions; and berate European and Asian allies about their inadequate defense spending without breaking the U.S. commitment to defend them. It will downplay human rights and may even look for deals with rogue regimes, such as North Korea.

You could hear both these predictions in Washington last week, sometimes from the same source, for the simple reason that nobody, probably including Donald Trump himself, really knows what he will do in foreign affairs. The fear is he will drive the world deeper into chaos and start a global trade war, or maybe a real war. The hope is that he will be tamed, as outsiders promising radical change frequently are, by sane advisers, the bureaucracy, Congress and — just maybe — a sense of the responsibilities of office.

We might not know for a while. But two big tests will show us where Trump is going, and the first will come quickly: appointments. The would-be Trump-tamers are fervently hoping he will choose to staff top national security posts with seasoned hands: Sen. Bob Corker (R-Tenn.) ; former national security adviser Stephen Hadley; David Petraeus. To do that they must overcome his strong inclination to install eccentric cronies such as Newt Gingrich, Rudy Giuliani or retired general Michael Flynn.

Gingrich may be out; journalist David Corn quoted him Sunday as saying he did not want to be secretary of state. But Giuliani, who reportedly wants it, is ignorant of foreign affairs. Flynn, who once sat next to Vladi­mir Putin at a dinner during a paid speaking trip to Moscow, is suspected of being a Russian stooge.

The top appointments matter because they will determine whether scores of Republican foreign policy professionals join or shun the new administration. If they sign up, policymaking may take a relatively conventional course. If not, the White House could resemble the Baghdad Green Zone early in the Iraq War, where eager but clueless political recruits steered the U.S. occupation toward disaster.

The other big test will be Trump’s handling of Putin. The president-elect’s creepily consistent defense of the Russian ruler during the campaign — Trump denied Moscow’s interference in the campaign even after he was briefed on it by the CIA — remains mysterious. Is Trump simply an admirer of Putin’s strongman strength, or does he somehow feel beholden to him, because of the hacking of Democratic emails or Russian investments in his businesses?

We may still be in the dark when Trump is sworn in. But if he follows up on his suggestion of an early meeting with Putin, we will start to see if the new president is different from Obama and George W. Bush, both of whom started by trying to cultivate the Putin regime. Putin will ask for the lifting of U.S. sanctions imposed because of Russia’s invasion of Ukraine, and for a U.S.-Russia alliance behind the Bashar al-Assad regime in Syria. Will Trump comply?

If he does, we will know that the global order is shifting. That’s because Trump’s stance toward Russia will shape his relations with key allies in Europe and the Middle East. If he betrays what has been solid Western support for Ukraine, NATO leaders, starting with Germany’s Angela Merkel, will be undermined and offended. Smaller nations in Central Europe will rush to make their own deals with Putin. If NATO’s recent deployment of troops to deter Russian aggression in the Baltic states crumbles, so will the alliance.

In Syria, U.S. alignment with Russia will quickly alienate America’s Sunni allies such as Saudi Arabia and Jordan, which see the Syrian civil war as a proxy fight with Iran. Trump has been contemptuous of some of those allies. But if he wants to defeat the Islamic State, he will need their help. Israel, too, wants to see the U.S.-Sunni alliance rebuilt. Prime Minister Benjamin Netanyahu, with whom Trump has promised warm relations, will be pressing for tough U.S. action against Iran, including an abrogation of the nuclear pact. Putin, a partner to the deal, will object to that, as will Merkel.

No doubt Trump has not even begun to grapple with these complications. He will have to soon. When he does, we will know if U.S. global leadership is headed for more of the slow erosion of recent years — or a radical collapse.

Read more from Jackson Diehl’s archive, follow him on Twitter or subscribe to his updates on Facebook.