By The Wall Street Journal

Donald Trump took the oath of office on Monday for a second term promising to disrupt the status quo — in Washington and around the world. Lord knows the status quo needs disrupting, but how he’ll do it and how far he’ll go remains a mystery, albeit for different reasons than eight long years ago.

In 2017 Mr. Trump had won narrowly, almost by accident, and he inherited a GOP majority in Congress that had a long-developed agenda on taxes, healthcare, judges and much else. The main policy victories of his first term — tax reform, energy development and judges — were traditional GOP priorities. He was less successful on his own signature issues of tariffs and immigration control.

This time Mr. Trump arrives in the Oval Office after a clear victory that was largely his own. The GOP majority in Congress is loyal to him, and a remarkable two-thirds of Republicans in the House were elected since 2016. Congress doesn’t have much of an agenda beyond what Mr. Trump campaigned on.

Eight years ago Mr. Trump also faced Democrats who were determined to oppose him on everything, if not impeach him from the start. There is no Russia collusion narrative this time. The press — which went all in for the “resistance” the last time — has hurt its credibility so much that Mr. Trump can afford to ignore most of its criticism.

The President-elect thus starts his second term with a personal favorable rating that is close to 50% and new political capital. Susie Wiles, his chief of staff, seems to have imposed order on the transition and the new White House staff. Mr. Trump’s first six months in 2017, by contrast, were a daily riot of media leaks and make-it-up-as-you-go orders.

All of this means Mr. Trump has political running room, though it’s not unlimited. His victory was solid but no landslide. Half the country still dislikes him. And the GOP majority in the House is so narrow that a couple of willful members can kill anything. Mr. Trump could quickly find himself in trouble if he exceeds his mandate from voters.

Take immigration and border security. Mr. Trump has a mandate to stop the flood of illegal migrants, and that will be an immediate priority. He will have support for deporting criminals and gangs like Tren de Aragua.

But he also promised mass deportation. If this means midnight raids on busboys, or separating mothers from children, the politics could turn fast. His best option is controlling the border and using his political capital on the subject to cut a deal with Congress on legal and illegal immigration.

Or take the tax bill that must pass to avoid a $4 trillion tax increase in 2026. Merely extending the 2017 tax provisions will be a heavy lift. But Mr. Trump campaigned on trillions of dollars more in tax breaks — no tax on tips, Social Security benefits or overtime. The danger is that the tax bill becomes a vehicle for income redistribution rather than economic growth. Inflation more than anything else elected Mr. Trump, and he will fail as President if his policies don’t lift real wages for his new working-class coalition. He needs to support the Federal Reserve’s efforts to keep reducing inflation and promote growth with supply-side tax and regulatory policies.

Which brings us to tariffs, which he calls the “most beautiful word” except perhaps “faith” and “love.” A tariff is a tax and a tax is anti-growth. Mr. Trump is going to impose tariffs as soon as his first week, and they may be large and universal. The impact of his tariffs, and of the retaliation from other countries, is a growth wild card. Congress has ceded so much authority to the President on trade that financial markets may be the only real check on his tariff policies. His policy advisers this time have all endorsed tariffs of some kind.

Mr. Trump also views tariffs as an all-purpose political tool, which raises the question of how much he wants to disrupt the current U.S. network of alliances. He may not leave NATO, at least not right away, but he will want Europe to provide for most of its own defense. Same with allies in Asia.

What we don’t know is whether Mr. Trump believes in a world in which there are dominant spheres of influence: the U.S. in the Western Hemisphere, China in the Asia-Pacific, and Russia in Europe. This is the logic of the GOP’s isolationist wing, and it is a recipe for a chaotic reordering of world affairs.

The biggest risk in our view is Mr. Trump’s desire to court adversaries in search of diplomatic deals for their own sake. He won’t settle the Ukraine war in a day as he promised, but an ugly deal that favors Russia could be his version of President Biden’s flight from Afghanistan. Mr. Trump will try again to coax North Korea’s Kim Jong Un into a nuclear deal, despite his failure the last time. Mr. Trump will be tougher on Iran at first, but he wouldn’t mind a nuclear deal with the ayatollahs if they’re willing.

Most important will be his courtship of Chinese dictator Xi Jinping. Former Trump security adviser John Bolton writes in his memoir that Mr. Trump said in his first term that a U.S. defense of Taiwan was implausible, and Mr. Xi can read. China could react to Mr. Trump’s tariffs with a blockade of Taiwan, or perhaps by taking nearby islands now controlled by Taiwan. How would Mr. Trump respond to avoid the risk of war? Would he cede Taiwan to Mr. Xi?

Mr. Trump’s victory was most important as a repudiation of the woke left, and it creates a rare opening for Republicans to build a new majority. But Americans don’t want disruption for its own sake. They will support it if it means broader prosperity that they can share. They also don’t want Mr. Trump to indulge in the politics of retribution by siccing the FBI and Justice Department on opponents.

If Mr. Trump focuses on settling scores rather than raising incomes, Democrats will sweep the 2026 midterms and progressives will return to power with a vengeance in 2028. A second presidential chance would be a terrible thing to waste.

— The Wall Street Journal