Panos Kammenos
© Reuters / Alkis KonstantinidisGreek Defense Minister and coalition partner Kammenos exits the Maximos Mansion following a meeting with Greek Tsipras in Athens, Greece, January 13, 2019.
Greece's defense minister has resigned in protest against a deal that would end a years-old dispute with Macedonia over its name. Panos Kammenos' exit could endanger the ruling coalition government ahead of national elections.

Kammenos submitted his resignation to Prime Minister Alexis Tsipras on Sunday. Speaking after the meeting, he said that "The Macedonia name issue... doesn't allow me not to sacrifice the minister's chair."

Following the news, Tsipras announced that he will call a confidence vote in his government next week.

Greece has a province called Macedonia and has repeatedly called on Skopje to change its country's name, which Athens considers an affront to Greek sovereignty. For years, Athens has blocked Macedonia's entry to the European Union and NATO, citing the name dispute.

The two countries recently agreed on a name change - the Republic of North Macedonia - but Kammenos said any deal including "Macedonia" in the name of the Balkan state to Greece's north was unacceptable.

Macedonia's parliament ratified the name change deal on Friday, but it will not go into effect until Athens does the same.

The country's main opposition, the conservative New Democracy party, said it will block the deal.

The Independent Greeks - the small party which Kammenos leads - formed a coalition with Tsipras in 2015, giving the prime minister a slim majority in parliament. Kammenos has vowed that he would also pull six other ministers from his party out of the government.

The future of the ruling coalition government remains unclear. Greece will hold parliamentary elections in October. Tsipras's coalition has 153 seats in the 300-strong parliament, 145 of them from his leftist Syriza party.