President Donald Trump has issued an astonishing new threat against Iran, posting a mocked up picture of himself brandishing an assault rifle with the strapline: “No more Mr Nice Guy!”

“Iran can’t get their act together,” the president wrote on Truth Social early Wednesday morning. “They don’t know how to sign a nonnuclear deal. They better get smart soon!”

The threat was accompanied by a meme of Trump, stood against a Middle Eastern backdrop of explosions devastating a hillside, wearing a dark suit and sunglasses and holding the heavy-duty firearm.

Talks with Iran have reached a stalemate after eight weeks of war, with another round of peace talks recently scrapped.

The president is currently hosting Britain’s King Charles III in Washington, D.C., for a four-day visit and said during an address in the East Room of the White House on Tuesday evening that the monarch “agrees” that Iran should never have a nuclear weapon, roping his majesty into the poltically-sensitive conflict.

“We’re doing a little Middle East work right now and we’re doing very well,” Trump said at the dinner.

“We have militarily defeated that particular opponent, and we’re never going to let that opponent ever – Charles agrees with me even more than I do – we’re never going to let that opponent have a nuclear weapon.”

A spokesperson for Buckingham Palace responded carefully: “The king is naturally mindful of his government’s long-standing and well-known position on the prevention of nuclear proliferation.”

Earlier Tuesday, the president wrote on his social media platform: “Iran has just informed us that they are in a ‘State of Collapse.’ They want us to ‘Open the Hormuz Strait,’ as soon as possible, as they try to figure out their leadership situation (Which I believe they will be able to do!)”

Tehran responded to the U.S.-Israeli airstrikes launched on February 28 as part of Operation Epic Fury by launching retaliatory strikes on its neighboring Gulf states that host American and Israeli military assets and then by blockading the strait, through which approximately one-fifth of the world’s oil passes, sparking a global surge in gas prices.

The U.S. military has responded by closing off Iran’s ports but the failure to find a diplomatic solution to the conflict while an uneasy ceasefire holds is proving an ongoing cause of tension around the world.

Also Tuesday, Trump lashed out at German Chancellor Friedrich Merz, posting: “The Chancellor of Germany, Friedrich Merz, thinks it’s OK for Iran to have a Nuclear Weapon. He doesn’t know what he’s talking about!

“If Iran had a Nuclear Weapon, the whole World would be held hostage. I am doing something with Iran, right now, that other Nations, or Presidents, should have done long ago. No wonder Germany is doing so poorly, both Economically, and otherwise!”

The president has insisted he is under “no time pressure” to reach a peace agreement with Iran and will prioritize a “good deal for the American people”, but a significant gulf remains between both sides on key issues, hence the decision to abandon a proposed second round of peace talks in Pakistan.

Experts have noted that while the closure of the strait is costing Tehran as much as $435 million a day, it has shown a far greater resilience than expected in the face of U.S. hostilites and have warned that a prolonged campaign could ultimately end up boosting the authoritarian regime.

While Trump has insisted he is under no immediate pressure to find a solution, he has midterm elections to win in November and will want to have his unpopular war wrapped up well before then, as concerns about its impact on the domestic economy continue to eat into his approval rating.

The president and Defense Secretary Pete Hegseth have repeatedly talked up America’s military successes in the conflict but Vice President JD Vance, known to be skeptical about the war, is reported to have asked privately whether Trump is getting accurate information about U.S. progress or is merely being told what he wants to hear by the Pentagon.