Jonathan Ernst / Reuters

President Donald Trump’s decision to quickly withdraw troops from Syria has sparked deep concern about an Islamic State revival, Iranian gains, and a Turkish attack on America’s Kurdish allies. For months, in both public and private, top aides—including Trump’s national-security adviser, his special envoy for the ISIS coalition, and his special representative for Syria—had all insisted that American troops were there to stay. Just one phone call with Turkish President Recep Tayyip Erdogan was all it took to upend the administration’s approach.

Trump’s tendency to agree spontaneously to requests pitched by foreign leaders, overruling his advisers, wreaks havoc on his administration’s agenda. His highly personalized, on-the-spot decision making disempowers and alienates his diplomatic team. But if past is prologue, there will be many more such episodes to come.

Jarring as the Syria decision was, it hardly marked the first time Trump suddenly agreed to a foreign suggestion over the explicit warnings of his officials.

In April, the U.S. Commerce Department slapped sanctions on the Chinese telecommunications company ZTE, charging that it had violated sanctions on Iran and North Korea and then lied about doing so. “This egregious behavior,” said Commerce Secretary Wilbur Ross, “cannot be ignored.” The sanctions were tough, barring U.S. suppliers from exporting parts to ZTE. Within a month, ZTE’s operations ground to a halt, and the company looked done for.

Until, that is, a call to Trump from Chinese President Xi Jinping. Xi urged a solution that would resuscitate ZTE, and within hours Trump tweeted that he was working “to give massive Chinese phone company, ZTE, a way to get back into business, fast.” The Commerce Department, he added, “has been instructed to get it done.” The White House issued a statement reassuring all that the president “expects Secretary Ross to exercise his independent judgment … to resolve the regulatory action involving ZTE,” but the die had been cast. The “personal favor” Xi asked for was granted, the sanctions were modified, and ZTE was put back in business.

Then there was the June Singapore summit with Kim Jong Un. Ahead of it, China for months floated a “freeze for freeze” scheme in which North Korea would halt its nuclear program while the United States suspended military exercises on the peninsula. Trump administration officials were unanimous in dismissing the proposal: Ambassador to the United Nations Nikki Haley called it “insulting,” and then–Secretary of State Rex Tillerson rejected an “approach in which legitimate defensive military exercises are placed on the same level of equivalency as the DPRK’s unlawful actions.” Privately, military leaders suggested that suspending exercises would degrade U.S. and South Korean readiness to fight if necessary.

No matter; ask, and Kim received. Immediately following their meeting, Trump announced at a press conference that he would halt the “war games” after all, catching administration officials, military leaders, and South Korean policy makers completely off guard. The exercises, the president said, are both expensive and “very provocative,” and so suspending them “is something that I think they very much appreciate.” The Pentagon subsequently canceled Freedom Guardian drills in August and another set of exercises in October. Freeze-for-freeze remains in place.

Spontaneous, personalized diplomacy isn’t always bad; it can break through decades of entrenched habit. In his famous 1986 summit with Mikhail Gorbachev, Ronald Reagan offered to eliminate all nuclear weapons within 10 years—a bold idea that would have set heads spinning among the high priests of deterrence. While the proposal at Reykjavik foundered on differences over the Strategic Defense Initiative, the talks paved the way for a 1987 ban on all intermediate nuclear forces, limits on nuclear testing, and the 1991 START treaty.

In Trump’s case, the merits of each decision are debatable; it’s the impulsive nature of his personalized diplomacy that’s the real problem. His pattern of behavior provides an incentive for allies and adversaries alike to bypass the very officials trying to carry out the president’s directives. Few countries will wish to negotiate with the White House or the State Department if they believe a better deal from the boss might be in the offing. This may be one reason Pyongyang has refused work-a-day negotiations over its nuclear program and is instead focused on holding a new, leader-to-leader summit.

Trump’s pattern also encourages pie-in-the-sky requests. In Helsinki, Trump entertained Vladimir Putin’s appeal for Russian investigators to question Americans—including Michael McFaul, a former ambassador to Moscow—about “illegal activities.” Trump rejected the idea after a bipartisan outcry, but other leaders surely learned from the episode that when the boss is in the room, anything is possible.

Successful foreign policy requires the president to fully empower a team that speaks for him. Trump’s habit of on-the-spot course reversals is like so much in our current political era: immediately satisfying but damaging in the long run. Expect more to come.

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