In mid-August, Austrian Foreign Minister Karin Kneissl danced with Russian President Vladimir Putin at her wedding — an act of bonhomie that raised eyebrows across a continent deeply skeptical of Russian foreign policy just months after an alleged assassination attempt on a former Russian spy in England.

But now Austria has been angered by its own allegations of Kremlin subterfuge. And on Friday, the Austrian government announced that Kneissl had canceled a trip to Russia planned for next month and summoned the Russian charge d’affaires.

Austrian authorities claim to have uncovered that a retired army colonel had been spying for Russia for several decades, beginning in the 1990s and continuing all the way up to this year. The Krone newspaper reported that the unnamed colonel had been paid the equivalent of $340,000 for confidential details about Austria’s air force and artillery systems. He could face up to two years in prison if found guilty.

Chancellor Sebastian Kurz said at a news conference Friday that if the allegations were confirmed, it would not improve the already strained relationship between Russia and the European Union. “Espionage is unacceptable,” he said, according to the Austria Press Agency.

Russian President Vladimir Putin attended the wedding of Austrian Foreign Minister Karin Kneissl on Aug. 18 in Gamlitz, Austria. (Reuters)

Kneissl also offered a warning that if the Austrian government’s suspicions were proved correct, it would place “a serious burden on the bilateral relations between Austria and Russia."

Russia has denied any knowledge of the spy scandal and summoned the Austrian ambassador to demand an explanation. Foreign Minister Sergey Lavrov told reporters that Austria was breaking the norms of international communications and conducting “megaphone diplomacy” by going public with the accusations so quickly.

“They accuse us in public and then demand public explanations over an issue we know nothing about,” Lavrov said, according to the Russian news agency.

The scandal could mark a turning point in relations between Russia and the new Austrian government. Vienna had previously sought neutrality in foreign affairs, trying to maintain ties to both Russia and its allies in the European Union. But when a coalition of the center-right People’s Party and the far-right Freedom Party gained control of the government last year, the country took a number of positions that appeared designed to draw it closer to Moscow.

In the aftermath of the poisoning of double agent Sergei Skripal and his daughter in Salisbury, England, this year, many Western nations expelled Russian diplomats. But Austria did not — and it has voiced opposition to E.U. sanctions on Russia.

Kurz also took stances on migration and other Europe-wide issues that have pitted it against powerful European leaders like Germany’s Angela Merkel — moves that were greeted warmly not only by a Kremlin often at odds with Europe, but also by President Trump’s ambassador to Germany, Richard Grenell, who called the young Austrian chancellor a “rock star.”

The country was seen as a possible link between Moscow and Washington and was mooted as a venue for a meeting between Putin and Trump. Finland was ultimately chosen instead.

Austrian Defense Minister Mario Kunasek said Friday that the alleged spying had come to light only a few weeks ago, following a tip from a friendly intelligence service. Though Austrian authorities have not named the country that supplied the information, Der Standard newspaper reported that it came from German intelligence officials.

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