Polish politician Donald Tusk on Thursday tweeted a photo of him pointing a pair of fingers toward President Trump’s back, a gesture some alarmed Twitter users likened to a gun.

“Despite seasonal turbulences our transatlantic friendship must last #Trump #NATO,” wrote Tusk, whose term as president of the European Council ended at the start of this month.

The friendly caption was offset by a photo of Tusk pointing his right index and middle fingers toward Trump, who had his back to the camera.

The move by Tusk — the former prime minister of Poland and a frequent critic of Trump — concerned some on social media, who felt that it had a menacing undertone.

“[Outgoing] European Union Council Leader Donald Tusk tweets himself holding 2 fingers against Trump’s back like a GUN,” tweeted user @justathoughtUSA. “Is that a THREAT?”

“We all know that the Globalist EU opposes Trump, but this goes too far,” continued the tweet, which tagged Trump and the FBI.

“what a disgusting gesture of @donaldtusk,” wrote user @Makaisia. “this moron has no manners!!!”

“Is this some sort of veiled EU threat aimed at the US?” asked a third user, @Dispropoganda.

Based on Tusk’s second hashtag, the photo apparently was taken at this week’s NATO summit, which took place in London.

Last month, Tusk was elected president of the European People’s Party — a conservative political party committed to strengthening the EU.

Tusk could not be immediately reached for comment.

The two Dons have had a fraught relationship.

In his final speech to the UN General Assembly in New York this September, Tusk took a sharp dig at Trump, calling his views on patriotism “false and dangerous.”

“To protect the truth, it is not enough to accuse others of promoting fake news,” he said, as reported by Politico. “Frankly speaking, it would be enough to stop lying.”

But many Poles were mortified by Tusk’s tweet, apologizing to Trump on Twitter on his behalf.

“As a Polish citizen I am embarrassed for this person,” wrote user @RZbijowski.

“Dear @realDonaldTrump, Poland apologizes for Donald Tusk,” added @MikiPoznan.