The first thing Cher did after coming off stage in London is peak Cher

Cher performing at the O2 Arena in London. (Getty)

Cher celebrated a triumphant set at London’s O2 Arena in the most Cher way possible – sub-tweeting Donald Trump in an all-caps rant.

Cher filled the O2 Arena on Sunday night for her first UK performance in 15 years.

Taking to the stage in an electric blue wig and a bedazzled toga (further costume and wig changes were, of course, incoming), she ran through a dizzying set of hits that covered her decades-spanning career.

After ending the night with a remixed version of her 1998 hit ‘Believe’, it appears that the first thing the singer did was to log straight onto Twitter.

At 10.37pm, moments after the concert’s 10.30pm curfew, she tweeted an article alleging that Turkey had used chemical weapons against civilians in Syria.

“HERES UR ‘KIDS IN A LOT’, U MURDERING FK‼️” she wrote.

“UR NOW A WAR CRIMINAL.U BRING ISIS BACK & ALL ‘UR ROADS WILL LEAD 2 PUTIN.’

“IF GOP COWARDS SMELL BLOOD…THEY’LL ‘DRAG U UNDER A?.'”

Cher calls Trump an ‘a**hole’.

Earlier in the night, Cher told the 20,000-strong London crowd that Trump is an “a**hole”.

“I could go off but we’re here to have fun,” she said.

“He’s an a**hole, and I don’t think Boris is much better. Those guys should go off together somewhere and fall in love.”

Gay icon is one of Trump’s most vocal opponents.

Since Trump took office in 2017, Cher has emerged as one of his most vocal celebrity critics.

Sunday night’s tweets were her latest criticism of the president’s widely-condemned decision to pull American troops from northern Syria.

Trump announced that the US would withdraw from the area on October 7, removing the buffer which had stopped Turkey from attacking the majority-Kurdish Syrian Democratic Forces (SDF), who were America’s allies in the fight agains ISIS.

Shortly after US troops withdrew, Turkish forces invaded.

According to the Syrian Observatory for Human Rights (SOHR), a UK-based monitoring group, more than 70 civilians have been killed and 300,000 others displaced during the week-long campaign.

On Thursday it was reported that six civilians had been treated for burns after a Turkish bomber dropped weapons containing illegal white phosphorus on a civilian town. Turkey has denied using any chemical weapons.

On the same day, Trump denied his decision to withdraw US troops, telling a rally: “Sometimes you have to let them fight, like two kids in a lot.

“You have to let them fight, and then you pull them apart.”

The rally was Trump’s first since the Republican and Democrats in the House of Representatives voted 354-60 to condemn his actions on Syria.