The Russian Ambassador to Britain has mocked the US by using an image from a stoner comedy film to depict a “terrorist”.

Alexander Yakovenko was writing about America’s reported ultimatum demanding that Iraqi chooses between Russia and the US for its continuing battle against Isis.

“US threatens to stop helping Iraq against ISIL if Baghdad asks Russia for help,” he wrote. "The terrorists must be rejoicing."

(Twitter)

The tweet was accompanied by a picture of actor Kal Penn wearing a headdress and fake beard in a clip from Harold & Kumar Escape from Guantanamo Bay.

The 2008 film told the story of the pair of friends being imprisoned in the notorious jail after being mistaken for terrorists on a flight to Amsterdam.

The clip shared by Mr Yakovenko shows Kumar laughing manically and miming the downing of a plane in the imagination of a fellow passenger, whose accusations later cause mayhem when his bong is mistaken for a bomb.

The irony of the moment being used by the Russian ambassador was not lost on Penn, who wrote on Twitter that it had been tweeted “with seriousness”.

“I can't stop laughing,” he added, before sending Mr Yakovenko a photo of Ivan Drago, a fictional Soviet boxer played in Rocky IV.

Penn is no stranger to diplomacy himself, having worked as the White House Associate Director of Public Engagement during breaks from his acting career.

President Bashar al-Assad met Vladimir Putin in a surprise visit to Moscow yesterday as disquiet about Russia’s support for the Syrian regime continued.

The Russian President’s spokesman said details of their discussions, revealed this morning, could not be shared but Mr Assad was understood to have thanked his counterpart personally for his military intervention.

Marine General Joseph Dunford, chairman of the Joint Chiefs of Staff, said today that the Iraqi government promised it would not request Russian support during talks in Baghdad.

He told reporters he set out a choice in a meeting with the Prime Minister and Defence Minister, saying: “I said it would make it very difficult for us to be able to provide the kind of support you need if the Russians were here conducting operations as well.

"We can't conduct operations if the Russians were operating in Iraq right now."

Prime Minister Haider al-Abadi said he would “welcome” Russian air strikes in Iraq earlier this month, after the Kremlin’s campaign began in neighbouring Syria.