Last week was bad for two nations. The first was Syria, which got 59 Tomahawk missiles slammed into it, destroying part of its air force, causing some casualties and losing the confidence that it could use nerve agents with impunity. The second was the United States, which launched those missiles and then, with some exceptions, roared its approval of what its president did. That will change soon enough. It was the right decision. It was just made by the wrong person.

Virtually up to the moment those missiles were launched, President Trump not only had an entirely different Syria policy, he in fact had none at all. In the preceding weeks, his White House spokesman, his secretary of state and his U.N. ambassador had all shrugged their indifference to the fate of Syrian President Bashar al-Assad. It came down to this: The White House didn’t give a damn.

Whether those foolish pronouncements encouraged Assad to have his air force apparently drop the nerve agent sarin on the hapless civilians of Khan Sheikhoun is not yet known. What is known is why Trump retaliated. He had seen television pictures of the slaughter and he was sickened. Assad would have to pay. Trump fired up the Tomahawks.

Assad had it coming. Even better, Trump reversed President Barack Obama’s shameful retreat from the brink back in 2012, when he warned Assad that the use of chemical weapons would cross a “red line” and then, a year later, when chemical weapons were used, shockingly, said oh, never mind. Even before that, Obama had refused to intervene in the Syrian civil war when it might have mattered. American inaction allowed the war to become a humanitarian catastrophe. Roughly 400,000 have died, and half the country has been displaced. Europe still reels from a tsunami of refugees clamoring to get in.

But Trump never cared about that. His stated policy was some absurdity called “America First” — and the rest of the world last. He pivoted in a flash. Why? Because he felt like it. His feelings may have been warranted, but next time — and there will be a next time — they may not be. He did not consult Congress nor wonder, it seems, where the decision to punish Syria would take him. Is “America First” dead? Is Stephen K. Bannon’s desire to let the rest of the world go hang now considered foolish? Is Trump’s recent declaration that he is president of the United States and not president of the world under reconsideration? I hope so.

The many commentators who cheered Trump’s missile strike ought to note that this is roughly what some of us feared: a cocksure president using the power of his office any way he wants. Trump will not be restrained by nettlesome constitutional questions nor the nagging examples of history. His respect for the Constitution is nil and history to him is, well, history — not on television, anyway. Not only will he do whatever he wants, but the success of the missile strike and the standing O it received will only encourage him.

Probably Trump will now get a bump in the polls. Presidents often do in the immediate aftermath of a military strike and none needed it more than Trump with an approval rating nosing under 40 percent. It takes a while for things to go wrong — remember the banner “Mission Accomplished,” which later came to mock the clueless George W. Bush? In the meantime, Trump will learn what all presidents do eventually — that when it comes to approval ratings, a military strike is better than infrastructure any day. It takes less time, too.

Trump is a special and worrisome case. He is by far the least experienced, least knowledgeable and least stable commander in chief in American history. No one else comes close — not even Harry S. Truman, who assumed office upon Franklin Roosevelt’s death with no knowledge of the very nuclear bomb program that would force Japan to surrender a mere five months later. Truman had at least been a senator. Trump had not a day of government or military service and, unlike the admirable Truman, is hardly a voracious reader.

Trump is now being thumped on the back for the swiftness of his decision, his disregard for the bureaucracy and the purity of his emotional reaction to the killings he saw on TV — so admirably American, so unlike the emotionally pinched Obama. Yet the precedent is there for a reckless presidential action by a reckless president. He will do this again because, as he just learned, he can.

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