Hungarian Prime Minister Viktor Orban. (Akos Stiller/Bloomberg News)

Rob Berschinski is the senior vice president for policy at Human Rights First. Hal Brands is the Henry Kissinger distinguished professor at Johns Hopkins University’s School of Advanced International Studies.

On May 13, President Trump will warmly welcome to the White House Viktor Orban, Hungary’s authoritarian prime minister, in a show of support long awaited by the Hungarian strongman. The visit is a grievous mistake — not just because it will be seen as an endorsement of a leader who has successfully dismantled a democracy, but also because it will signal affirmation of an agenda that is fundamentally threatening to transatlantic security.

Orban is not, of course, the first strongman on whom Trump will shower kind words. From Vladimir Putin to Kim Jong Un, Recep Tayyip Erdogan to Abdel Fatah al-Sisi, Mohammed bin Salman to Rodrigo Duterte, Trump has fawned over some of the world’s most corrupt and anti-democratic leaders not named Maduro or Ortega.

Yet even among this august assemblage, Orban stands out. Over the past nine years, the Hungarian leader has accomplished many of the anti-democratic actions Trump can only tweet about. He has rewritten Hungary’s constitution and dismantled judicial checks on power, stifled a once vibrant media, forced a top university out of the country, and criminalized the activities of some human rights organizations. Meanwhile, he has won deeply flawed elections by vilifying migrants, Muslim “invaders” and the Jewish “financiers” that supposedly support them.

In parallel, Orban’s government — a NATO ally — has drawn closer to Russia. The Hungarian leader’s attacks on the media and nongovernment organizations echoes the tactics of Putin. Meanwhile, Orban has impeded efforts to deepen NATO’s engagement with Ukraine and helped Moscow protect suspected Russian arms dealers from the U.S. Justice Department. He has also voiced support for Russia’s annexation of Crimea — contrary to official European Union and NATO positions on the issue. Even more worrying, many U.S. and European observers believe that the Hungarian government has been so thoroughly penetrated by Russian intelligence that it acts as a sort of Trojan horse within NATO.

The Trump administration has responded to this worrying pattern by embracing the Hungarian government. The administration’s logic is that by accommodating Orban’s assault on the rule of law, the United States can keep its ally “on side” against Russia while perhaps selling it arms. Yet this strategy is backfiring.

The administration’s accommodationist policy certainly doesn’t reflect America’s stated values, and it also doesn’t make strategic sense. It’s no coincidence that Orban has drawn closer to Putin as he has abandoned liberal democracy — authoritarian birds of a feather flock together.

And while anti-democratic, pro-Russian behavior undertaken by a NATO ally raises several immediate security-related challenges, the full scope of the danger presented by Orbanism is even greater. That threat comes from how the Hungarian leader is revising the darker chapters in European history to benefit his party’s hold on power.

Orban’s ongoing efforts to rewrite Hungary’s role in the Holocaust are as well-documented as they are troubling. Less well understood, however, are the actions and rhetoric he employs in support of Hungary’s claims to territory lost after World War I.

During the Great War, the Austro-Hungarian empire fought alongside Germany, ultimately losing to the Allied powers led by Britain, France and the United States. While the Treaty of Versailles formally ended the war with Germany, the Allies struck a separate agreement with Hungary known as the Treaty of Trianon, which left modern Hungary a rump state. The interwar Hungarian government decided to join Germany as an Axis power during World War II largely as a means to reclaim territories lost two decades prior.

Since emerging from Soviet domination, Hungarian leaders have accepted modern Hungary’s borders, recognizing the explosive implications of irredentism in European history. Hungary’s admission to NATO in 1999 was contingent upon Budapest accepting its territorial status quo. Yet Orban and the ethno-nationalist far-right he represents have revived this long-dormant issue. The Hungarian prime minister actively supports the historical rehabilitation of Hungary’s interwar rulers, leaders he has called “exceptional statesmen.” He’s even gone so far as to plan a memorial in Budapest to Trianon and “Greater Hungary,” a none-too-subtle signal of where he stands on recovering lands lost nearly a century ago.

Europe will commemorate the centennial anniversary of the Versailles Treaty this summer and the Treaty of Trianon in 2020. Between now and then, Orban is likely to escalate his nationalist rhetoric. Analysts differ on whether his support for “Greater Hungary” is authentic or just red meat for his political base. In reality, such distinctions matter little. Irredentist talk, in Europe’s historical context, is playing with fire.

It is unlikely that Trump will raise any of this with Orban. And it may take years for the ramifications of the prime minister’s ethno-nationalism to fully materialize. Yet, as is sometimes said, history rhymes, and the tune Viktor Orban sings is a threat to international security. The man has no business in the Oval Office.

Read more:

James Kirchick: Is Hungary becoming a rogue state in the center of Europe?

The Post’s View: The ouster of Central European University marks a dark day for Hungary

Anne Applebaum: Hungary is thumbing its nose at the U.S. — by following Trump’s cues

The Post’s View: Democracy’s slow fade in Central Europe

Lally Weymouth: An interview with Viktor Orban, prime minister of Hungary