According to a formal whistleblower complaint, President Donald Trump withheld Congressionally‐​appropriated aid from Ukraine in an attempt to pressure Ukraine’s new president, Volodymyr Zelensky, to investigate Trump’s 2020 political rival, former Vice President Joe Biden. In addition to seeking dirt on Biden, Trump also asked Zelensky to help locate the computer server allegedly used by the Democratic National Committee that was hacked by Russia, suggesting that Trump is intent on relitigating the Mueller investigation into the 2016 campaign.

Although Trump has tried to pass off this episode as entirely above board, he did all this largely outside official channels. Rather than going through the normal interagency process to carry out official policy, Trump tasked his personal lawyer Rudy Giuliani and several other loyalists to do his dirty work “off the books.” The White House also engaged in an attempted cover up of this chicanery, according to the complaint.

The controversy brings to mind a famous New York Times op‐​ed published a year ago. In it, an unnamed senior administration official, claiming to be a part of an internal resistance against the president, identified Trump’s “amorality” as “the root of the problem.” “Anyone who works with him,” the official explained, “knows he is not moored to any discernible first principles that guide his decision making.”

We agree. It is clear from the whistleblower complaint, the rough transcript of the Zelensky call, and Trump’s own public confessions that the president put his personal political interests above the national interest. While the revelations are shocking, they should not be surprising.

We study international relations, so that’s our frame for analyzing, in our forthcoming book, what drives Trump’s decision‐​making. To be sure, President Trump is a hard case. His foreign policy preferences often defy neat categorization, and many of his positions change with the political winds — sometimes even within a single news cycle. The president’s mercurial personality and psychological makeup, and his apparent lack of a fixed ideology, make it difficult to define his worldview with precision.

But it is possible to work out certain consistent features of Trump’s overall worldview that drive his approach to foreign affairs. And his apparent attempt to shake down a foreign leader to provide dirt on a political opponent makes perfect sense in light of these defining features.

First, Trump is driven by zero‐​sum transactionalism. This mentality pervades his thinking across personal and political domains, and explains his views on trade, alliances, and multilateral agreements. His record in office so far strongly suggests that ethical and strategic imperatives matter far less than whether Americans – or, more often, him personally – can gain at the expense of others.

This calculated transactionalism is reflected not only in Trump’s attempt to use the power of his office to further his own narrow election interests, but also in his expectation that Zelensky’s only concern would be narrow self‐​interest. Ukraine desperately wanted the U.S. military aid Trump withheld, and the president expected a simple zero‐​sum transaction — a quid pro quo, if you will.

Second, Trump is a stereotypical Jacksonian. “Jacksonian political philosophy,” explains the political scientist Walter Russell Mead in a 2001 book, “is often an instinct rather than an ideology…a set of beliefs and emotions rather than a set of ideas.” Jacksonians, according to Mead, are disposed “toward conspiracy thinking” and are willing to deploy the powers of the presidency “even at the cost of constitutional niceties.” That political leaders “employ vigorous measures” is more important to Jacksonians “than to worry about the niceties of international law.”

Indeed, Trump’s attempt to pressure Ukraine was driven in part by a stream of debunked conspiracy theories circulating on the fringes of the right‐​wing online media. One such theory alleges that Ukraine, not Russia, interfered in the 2016 elections on behalf of the Clinton campaign. Another claims that Vice President Joe Biden pressured Ukraine to fire its prosecutor in order to relieve his son, who was then on the board of a Ukrainian company Burisma Holdings, of scrutiny for corruption (in fact, the prosecutor was failing to go after corruption, the investigation into Burisma had gone dormant, and Ukraine’s current top prosecutors says publicly that there is no evidence of wrongdoing on the part of the Bidens).

Third, Trump is obsessed with his own reputation. In a review of five hours of recorded interviews with Trump con­ducted by his biographer in the mid 2000s, the New York Times’s Michael Barbaro identifies Trump’s “deep‐​seated fear of public embarrassment” as his most powerful driving force. “The recordings reveal a man who is fixated on his own celebrity” and “anxious about losing his status.”

Again, this helps explain Trump’s determination to get information from Ukraine. The finding of the U.S. intelligence community and Special Counsel Robert Mueller that Russia meddled in the 2016 election to help the Trump campaign undermines the legitimacy of his election. Overturning that narrative by getting to the bottom of these Ukraine conspiracy theories required pressuring Kiev outside of official U.S. channels, something Trump apparently had few qualms about.

Finally, Donald Trump’s inclinations are unusually authoritarian by the standards of contemporary U.S. political culture. Scholars have been researching authoritarian personality traits in political leaders for decades. Authoritarians tend to share important psychological habits and decision‐​making styles. They have greater difficulty engaging in critical thinking, are more likely to blame scapegoats for societal problems, are given to superstition and stereotyping, place a high value on power and toughness, and tend to abuse and intimidate subordinates, thus suppressing an open and deliberative decision‐​making process.

Donald Trump exhibits all of these characteristics in spades. He demands loyalty from officials in federal departments that are supposed to be independent and nonpartisan. Trump has repeatedly attacked federal courts as illegitimate, and leveled ad hominem attacks against individual judges who had the gall to overrule his executive orders. He vilifies the press as “the enemy of the people.” He has recklessly accused the whistleblower of being a spy and Rep. Adam Schiff, who is leading the impeachment inquiry, of treason.

For President Trump to conduct his foreign policy in this way makes sense, given his character and his worldview, but that does not mean it is acceptable. It should make Americans rethink not just the expanded powers of the presidency, but U.S. foreign policy in general.

America’s outsized role in the international system is in part justified on the grounds that U.S. leadership is morally superior to the alternatives and that America is guided by higher principles. One need not confine oneself to the Trump years to appreciate the weakness of this claim.

But Donald Trump does clarify the danger. His ascendance to the highest office in the nation is per­haps the most compelling illustration of the hazards of vesting the pres­idency with so much unbridled power, both domestically and internationally. The presidency, and the global military presence it commands, must be cut down to size and properly checked by its co‐​equal branch. With or without Trump, any world order that depends for its survival on the whims of a single person in a single branch of gov­ernment in a single country is simply untenable.