Donald Trump has warned Iran that an attack on "anything American" will be met with "great and overwhelming force", with parts of the country facing "obliteration".

The US leader issued the threat as he criticised "ignorant and insulting" remarks by Iran's president, who had earlier mocked Mr Trump by claiming the White House was "afflicted by mental retardation".

Hassan Rouhani said fresh US sanctions imposed on Iran's Supreme Leader Ayatollah Ali Khamenei and his associates were "outrageous and idiotic", amid escalating tensions between the two countries.

Image: Mr Trump signed off fresh sanctions targeting Iran's supreme leader on Monday

In a series of tweets posted on Tuesday, Mr Trump said Iran's "very ignorant and insulting statement... only shows that they do not understand reality".

"Any attack by Iran on anything American will be met with great and overwhelming force," he added.


"In some areas, overwhelming will mean obliteration. No more John Kerry & Obama!"

Mr Trump said Iran's leadership could not comprehend the words "nice or compassion" and only understood "strength and power", with the US "by far the most powerful military force in the world".

The US president tweeted: "The wonderful Iranian people are suffering, and for no reason at all. Their leadership spends all of its money on terror, and little on anything else."

Iran's foreign ministry has said the latest US sanctions could spell a "permanent closure" to diplomacy between the two countries after Tehran shot down an unmanned American drone last week.

Image: The US military has denied it had a drone over Iran. File pic

Mr Trump initially told reporters the sanctions were in response to the attack on the aircraft, but later claimed they would have been imposed regardless of the incident.

Russia has said it would counteract the sanctions on Tehran, which it has branded "illegal", and called for dialogue between the US and Iran.

Moscow has also supported Iran's claim that the drone was in Iranian airspace when it was downed and said that US evidence alleging Tehran was behind attacks on American ships in the Gulf of Oman was poor quality and unprofessional.

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National security adviser John Bolton has said Mr Trump is open to negotiations and "all that Iran needs to do is walk through that open door".

Meanwhile, British Foreign Secretary Jeremy Hunt, who is one of two contenders to be the country's next prime minister, has said he "can't envisage any situation" in which the UK would go to war with Iran.

He told MPs that the Foreign Office was "very concerned about the situation in the Middle East and the risks of an accidental war".

Mr Hunt added: "We've made serious efforts to de-escalate tension, including a visit by my friend the minister for the Middle East to Tehran at the end of last week."

The White House has launched cyber attacks against Iran earlier this week, saying it disabled the country's intelligence systems which controlled its rocket and missile launchers.

It came after Mr Trump said last week that he pulled out of airstrikes in retaliation for Iran's downing of the US drone because it would have killed 150 people.

Tensions between the two countries have been rising since the US pulled out of a 2015 nuclear deal that world powers signed with Iran and reinstated crushing sanctions on the country's economy.