Just days after saying he was prepared for talks, United States President Donald Trump has issued a direct threat to Iran, suggesting that the Islamic republic will be destroyed if it attacks his country’s interests.

“If Iran wants to fight, that will be the official end of Iran. Never threaten the United States again,” Trump wrote on Twitter on Sunday. He did not clarify what threats he meant.

The confrontational post follows last week’s attacks on Saudi oil assets and the firing of a rocket on Sunday into the heavily fortified “Green Zone” in Iraq’s capital, Baghdad, an area housing many government buildings and embassies.

The Iraqi military said there were no casualties in the rocket attack. There has been no claim of responsibility.

Amid escalating tension with Iran, Washington earlier this month dispatched to the region an aircraft carrier and B-52 bombers, as well as an amphibious assault ship and a Patriot missile battery.

On Wednesday, it ordered the evacuation of non-essential personnel from the US embassy in Baghdad embassy and the Erbil consulate in northern Iraq, citing “imminent” threats from Iranian-backed Iraqi armed groups. It did not disclose any details, and its account has been met with widespread scepticism outside the US.

But in recent days, the White House has sent mixed signals over its stance against Iran, amid multiple US media reports of infighting in Trump’s cabinet.

John Bolton, Trump’s long-hawkish national security adviser, is reportedly pushing a hard line on Iran, but others in the administration are resisting. Trump himself said recently that he has to “temper” Bolton.

And when he was asked on Thursday if Washington was going to war with Tehran, Trump replied, “I hope not”. That comment came a day after he expressed a desire for dialogue, tweeting: “I’m sure that Iran will want to talk soon.”

“It really is becoming clear that this administration is sending mixed messages when it comes to Iran,” Al Jazeera’s Patty Culhane, reporting from Washington, DC, said.

“So the big question is why did he send that confrontational tweet? Is it because he received some sort of classified briefing or is it because of something he watched on television? We don’t know.”