His call with Ukrainian President Volodymyr Zelensky was "perfect," President Trump said Sunday, but whether we the public will be permitted to read a transcript of this perfection remains to be seen. A certain expectation of privacy is essential to high-level talks, the president argued: "The problem is, when you're speaking to foreign leaders, you don't want foreign leaders to feel that they shouldn't be speaking openly. And the same thing with an American president." So maybe the details of the call will come out, but if they don't, Trump suggested, it's for diplomacy's sake.

This argument is fair enough on its face — but the surrounding circumstances have rendered it a farce. Diplomatic discretion certainly has its value, but surely that consideration pales next to our need to settle the merits of serious allegations that the president abused U.S. foreign policy for personal political gain. And if those accusations are true, Trump's use of diplomacy here — both in the initial corruption and in his attempt to hide it — creates a danger that runs beyond the immediate scandal: It undermines diplomacy in the American polity at a moment when we need it most.

Trump as a threat to diplomacy is nothing new. He fancies himself a master dealmaker, which is demonstrably false. His negotiating instincts know nothing of concession and cooperation, only coercion. He is all sticks, no carrots. He recklessly rejects or withdraws from deals others have constructed without any apparent consideration of probable consequences. He seems to care far more about his personal receipt of glory — "credit," in Trump's phrasing — for a diplomatic accomplishment than whether the accomplishment happens at all.

"It should be enough that the U.S. secures an agreement that serves our country's interests, but the president would rather lose the agreement than miss out on the pomp of a summit," wrote The American Conservative's Daniel Larison of U.S.-Taliban talks to end the war in Afghanistan earlier this month. "If [Trump] cannot be seen personally as the great dealmaker, he would prefer failure. For that matter, he tolerates policy failure as long as he gets to play the part of the high-stakes negotiator. Results are irrelevant. All that matters to him are the ratings and the images."

This personalization of diplomacy is central to Trump's negotiating style. In one single sense, it is tolerable: If Trump enjoys talks and what they do for his image, he is more likely to pursue talks than to incessantly give into his baser instincts of militarism. The sole virtue of his "I alone can fix it" style of diplomacy is that it is still diplomacy and, therefore, not simple indulgence in the "bomb the sh-- out of ‘em" foreign policy to which this president often gravitates.

But "better" is not "good," and Trump's personalized diplomacy is far from desirable. It is inherently erratic, shifting with the president's volatile moods and influences. Feelings outweigh national interest. Progress is easily stalled, as foreign leaders' rejection of Trump's terms is interpreted as rejection of Trump himself (and vice versa). Any wins are heralded as personal accomplishment and evidence of great friendship or even "love;" policy differences are taken as personal insult.

This dynamic at least partially informs the contrast between the Trump administration's approaches to North Korea and Iran. "The president remains favorably disposed towards Kim because the dictator butters him up and because he has been willing to play along with the photo op summits," Larison argues, but the "Iranian government has so far refused to indulge Trump in these empty displays, and so he remains as hostile to them as ever." (Maybe the fastest way to stave off yet another Middle East boondoggle is for Ayatollah Khamenei to send Trump a flattering tweet.)

If he indeed withheld congressionally-allotted aid to Ukraine to coerce an investigation of the Biden family, Trump's personalization of diplomacy has reached a new low. It moves past a generalized, vainglorious incompetence to direct corruption. But whether we see this as a change of degree or kind, the risk to the credibility and practice of American diplomacy is grave.

After 18 years of constant war, we desperately need a renewed commitment to diplomacy as the default tool of U.S. foreign policy. If negotiations are tied to Trumpian pettiness and extortion, such a shift becomes much more difficult. The link fuels hawks' claims that negotiations have been tried and found wanting. In this way, Trump's deficiency and dishonesty could impair U.S. diplomacy for years to come.