In a dramatic turn of events, the administration of French President Emmanuel Macron has recalled its ambassador to Italy in retaliation for an “unacceptable” meeting between Italian Deputy Prime Minister Luigi Di Maio and French protesters.

Traveling in France this week, Di Maio met and posed for a photo op with organizers of the French “yellow vest” anti-government movement.

“This new provocation is unacceptable between neighboring countries and partners at the heart of the European Union,” a French Foreign Ministry spokesman said in a press briefing.

“Mr Di Maio, who holds government responsibilities, must take care not to undermine, through his repeated interferences, our bilateral relations, in the interest of both France and Italy.”

The action to recall France’s envoy to its European ally is a rare occurrence within the region, and it is the first time relations between Paris and Rome have deteriorated to such a point since the start of World War II.

Di Maio – part of Italy’s populist anti-establishment movement that was swept into power last year – declared in a Twitter post on Tuesday that “the winds of change have crossed the Alps.”

The yellow-vest movement spread like wildfire last year in response to policies enacted by the Macron administration, bringing the French president’s reform initiatives to an abrupt halt.

The demonstrations have drawn support across the political spectrum, especially among rural populations, in response to a high cost of living exacerbated by recent tax reforms. Anti-government voices within the movement have called for populist policies including a wealth tax and a minimum wage increase.