Heather A. Conley is senior vice president for Europe, Eurasia and the Arctic at the Center for Strategic and International Studies (CSIS) in Washington and was a deputy assistant secretary of state from 2001 to 2005.

Outsiders might be surprised to hear that some Hungarians mourn the loss of empire — Hungarian Prime Minister Viktor Orban first among them. On Thursday, he will unveil a Memorial of National Unity that includes the names of 12,000 historic municipalities “torn from their homeland” following the signing of the Treaty of Trianon, which formally ended the Austro-Hungarian Empire and the Kingdom of Hungary 100 years ago. The commemoration ceremony will be merely the latest installment of Orban’s long-running manipulation of history for the sake of his own political agenda and continuation of power.

In the wake of World War I, the victorious Allies imposed harsh punishments on the Central Powers. While historians mostly concentrate on the severity of the terms imposed on Germany in the Versailles Treaty, the Kingdom of Hungary, as one of the constituent parts of the Austro-Hungarian “Dual Monarchy,” arguably suffered even worse. In the Treaty of Trianon, formalized on June 4, 1920, Hungary lost 72 percent of its prewar territory and 64 percent of its population.

The loss of empire remains palpable today. Visit a Hungarian official’s office and you will sometimes see a framed map of pre-Trianon Hungary on the wall, perhaps including small vials of soil from the “lost lands” in modern-day Slovakia, Ukraine, Romania or Serbia. Orban has proven remarkably adept at mobilizing this nationalist nostalgia.

In recent years, Orban’s government has downgraded public commemoration of Hungarians who embody more democratic values while actively promoting memorials to Hungarian leaders allied with Hitler and Mussolini during World War II. Most notoriously of all, Orban has embraced Regent Miklos Horthy, Hungary’s fascist and anti-Semitic dictator in the 1930s, precisely because under Horthy’s leadership a portion of Trianon was overturned with Hungary’s spiritual heartland province of Transylvania annexed in 1940. (Transylvania was restored to Romania, where it had spent most of the interwar period, on March 6, 1945, after the Horthy regime’s collapse in 1944.)

Since he returned to power after a spell in the opposition in 2010, Orban pushed through the passage of a law enabling foreigners who had a Hungarian ancestor and “knowledge” of the Hungarian language to receive Hungarian passports. Of several million who were eligible, some 700,000 had received citizenship by 2015. In 2013, Orban urged ethnic Hungarians around Europe “to unite” in order to make the country “a strong nation.” In 2014, in his annual summer speech in Romania (which is still home to approximately 1.5 million ethnic Hungarians today), Orban acknowledged that he owed his sweeping electoral victory earlier that year to the voting rights of ethnic Hungarians living abroad. That was the same speech in which he declared his aspiration to transform Hungary into an “illiberal state.”

Over the past decade, Budapest has purchased media outlets and publications to exclusively serve Hungary’s ethnic communities. The Hungarian government generously funds sports clubs, schools and churches in ethnic Hungarian communities that are close to its borders. As a result, some ethnic Hungarian communities have effectively decoupled from the countries in which they live, relying largely on media and cultural institutions imported from Hungary. Orban’s policies in this respect are reminiscent of Russia’s tactics in its own “near abroad.”

Clearly, Orban cannot reconstitute a pre-Trianon Hungary by re-annexing parts of Romania, Slovakia or western Ukraine. Nonetheless, his efforts to bind Hungary closer to its “lost lands” have destabilized the region and complicated U.S. foreign policy objectives. Budapest’s singular focus on its ethnic population in Ukraine has prevented any high-level meetings from taking place between NATO and Ukrainian officials for the past two years.

Tensions between Romania and Hungary, both NATO members, are running particularly high at the moment. The more Budapest promotes heavy-handed ethnic activities and symbols in Transylvania, the more the Romanian authorities feel compelled to assert their nationalism, heightening anti-Hungarian sentiment and creating a vicious cycle that only strengthens ethno-nationalism and grievance-based politics across the region.

Orban uses Trianon opportunistically. As he notes, the ethnic Hungarian communities beyond Hungary’s borders deliver the votes he needs to keep him in power — a factor likely to become even more important as his political party loses control of major Hungarian cities. Yet his cynical efforts to capitalize on the sense of historical resentment among his compatriots now threaten to inflame precisely the same destructive nationalism that led to World War I — and the subsequent loss of Hungary’s imperial privileges. I wonder if Hungary’s leader fully appreciates the irony.

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