Donald Trump says he's not going to 'need an exit strategy' if the U.S. goes to war with Iran.

He told reporters in the Oval Office on Tuesday that he wasn't attempting to send Tehran a message with a tweet he sent earlier in the day and admitted he had no plan to get the country out of a messy military conflict if the situation escalates.

'You’re not going to need an exit strategy. I don’t do exit strategies,' he told a reporter, who asked him about him the possibility of war.

Trump threatened Iran with 'obliteration' if it attacks 'anything American' earlier in the day, after the country's president branded the White House 'mentally retarded' after Trump issued fresh sanctions against the leadership in Tehran.

He launched a fusillade of tweets calling the country's leadership 'ignorant and insulting' after the insult from its president, Hassan Rouhani.

'Iran’s very ignorant and insulting statement, put out today, only shows that they do not understand reality,' he said. 'Any attack by Iran on anything American will be met with great and overwhelming force. In some areas, overwhelming will mean obliteration. No more John Kerry & Obama!'

Donald Trump says he's not going to 'need an exit strategy' if the U.S. goes to war with Iran

A White House official cautioned DailyMail.com against interpreting the president's Twitter tirade as a new threat of military action, after the president last week called off a military strike.

And Trump told a journalist in the Oval later, 'There is no message. You know what, I’ll tell you what the message is: When they’re ready.'

'When they’re ready, they’ll let us know,' he said before he unloaded on his predecessor and the former secretary of state again.

The outburst is the latest in a back and forth with Iran that came to the brink of a bombing Iran in retaliation for Tehran's shooting down a Navy spy drone in what the U.S. says was international airspace.

Trump publicly told the Iranian leadership that he was open to talks, but clearly took offense at Rouhani, who said that America is lying about wanting to negotiate and only proves that Washington is desperate and running out of options.

He said he was 'ready to do whatever' and said it 'doesn’t make any difference' to him what Iran decides. 'Whatever they want to do, I'm ready. Okay?' he said of possible talks.

The U.S. president put new sanctions on Tehran into effect on Monday. He used them as an alternative punishment for an attack on an unmanned drone after backing away from a strike he says would have killed 150 Iranians.

Hassan Rouhani has branded Donald Trump 'mentally retarded' over 'outrageous and idiotic' new sanctions imposed on Iran, which he says proves the US does not want to negotiate

It comes after Iran's foreign ministry spokesman Abbas Mousavi warned that targeting Iran's ayatollah with new measures would close the door on diplomacy

Speaking to a session of ministers that was broadcast on TV, Rouhani said the new sanctions are 'outrageous and idiotic' and will fail because Ayatollah Khamenei - one of the main targets - has no foreign assets for Trump to sanction anyway.

Rouhani pointed to sanctions leveled against Foreign Minister Mohammad Javad Zarif as evidence that Washington is not looking for a discussion.

He said: 'You sanction the foreign minister simultaneously with a request for talks?'

Rouhani spoke shortly after National Security Advisor John Bolton insisted that Washington had 'held the door open to real negotiations' and that 'in response, Iran's silence has been deafening.'

Also on Tuesday, Iran's foreign ministry spokesman Abbas Mousavi warned that new sanctions would permanently close the door on negotiations.

'Trump's desperate administration is destroying the established international mechanisms for maintaining world peace and security,' he tweeted.

Mousavi said the 'fruitless sanction on Iran's leadership and the chief of Iranian diplomacy mean the permanent closure of the road of diplomacy with the frustrated U.S. administration.'

Trump enacted new 'hard-hitting' sanctions Monday targeting Iran's Supreme Leader Ayatollah Ali Khamenei pictured above on June 19

Secretary of State Mike Pompeo speaks during a news conference at the U.S. Embassy in Kabul, Afghanistan. He's in the country that has been dubbed the endless war for how long the U.S. has had troops there

This comes amid heightened tensions between Iran and the U.S. after the Trump administration tore up a nuclear deal signed under Obama, before Iran last week shot down a $100 million U.S. Navy surveillance drone.

On Monday Trump signed an executive order with the 'hard-hitting' sanctions on Iran directly targeted at Supreme Leader Ali Khamenei after what he called a 'series of aggressive behaviors' by the regime that included the drone attack.

He said the ayatollah's own finances would now be in U.S. crosshairs as he stepped up the rhetoric against Iran, despite calling off U.S. airstrikes minutes before planes were due to take to the air on Thursday night.

'I'll be signing an executive order imposing hard-hitting sanctions on the supreme leader of Iran on the office of the supreme leader of Iran and many others. Today's action follows a series of aggressive behaviors by the Iranian regime in recent weeks, including shooting down of U.S. drones,' Trump said in the Oval Office on Monday.

He added, 'We do not seek conflict with Iran or any other country,'

'I think a lot of restraint has been shown by us – a lot of restraint – and that doesn't mean we're going to show it in the future,' he said. 'But, I felt that we want to give this a chance, give it a good chance, because I think Iran potentially has a phenomenal future.'

Tensions between the two nations exploded last week after initial sanctions against Iran led to the attacks on two oil tankers in the Strait of Hormuz. e U.S. blamed that attack on Iran, which has denied involvement. An oil tanker pictured on fire in the sea of Oman on June 13 above

This file image released by the U.S. Department of Defense Monday, June 17, 2019, and taken from a U.S. Navy helicopter, shows what the Navy says are members of the Islamic Revolutionary Guard Corps Navy removing an unexploded limpet mine from the M/T Kokuka Courageous. A series of attacks on oil tankers near the Persian Gulf has ratcheted up tensions between the U.S. and Iran

U.S. officials also said they planned sanctions against Zarif, the foreign minister and a chief negotiator of the nuclear deal that Trump despises and pulled the nation out of.

Washington says the new measures were taken to discourage Tehran from developing nuclear weapons and supporting militant groups

Tensions between the two nations have been steadily building since America backed out of the international nuclear pact signed with Iran and reimposed sanctions.

Last month, two oil tankers were attacked in the Strait of Hormuz - a strategically important bottle-neck through which much of the world's oil supply flows - that America and Saudi Arabia blamed on Iran.

The spurred the U.S. to deploy a carrier strike group to the region and send extra troops to counter what it described as a 'credible threat' against its forces.

Then, on June 13, two more tankers were attacked and the US again pointed the finger at the regime in Tehran.

Intelligence services subsequently released what they said was footage of Iranian vessels returning to collect limpet mines used in the attack which had failed to explode in an effort to cover their tracks.

Last week, Tehran shot down a $100 million US Navy drone which it claimed had violated its airspace. America denied this, calling it an 'unprovoked attack'.

Treasury Secretary Steve Mnuchin told reporters that the administration will 'lock up literally billion dollars in assets' of Iran's

President Donald Trump signs an executive order imposing fresh sanctions on Iran as Treasury Secretary Steven Mnuchin and Vice President Mike Pence look on

President Trump approved airstrikes against a number of Iranian targets but backed down at the last moment, saying the response would not be 'proportionate,' as no American were actually killed.

Instead, the U.S. military carried out a cyberattack against Iranian missile systems and a spy network, Fox Newsreported.

'Now along with our existing sanctions authority, we have additional sanctions to go after the supreme leaders' office and lock up literally billions of dollars more of assets,' Treasury Secretary Steve Mnuchin told reporters at a hastily-arranged White House press briefing.

He said, 'These sanctions are highly, highly-effective in locking up the Iranian economy.'

Mnuchin said the order was in the works before last week's downing by Iran of a U.S. military surveillance drone and indicted it was in response to that as well as to previous Iranian actions in the Gulf, including attack on the oil tankers.

The president also warned Tehran it can never have a nuclear weapon.

How the claims differ: Iran and the U.S. differ on where the drone was when it was targeted

A RQ-4 Global Hawk unmanned air drone

'We cannot ever let Iran have a nuclear weapon and it won't happen and secondly, and very importantly, we don't want money going out to sponsor terror. They are the number one sponsor of terror in the world. So I'll sign this order right now,' Trump said.

The United States pulled out of a 2015 nuclear deal that world powers signed with Iran and has applied crushing sanctions on the Islamic nation.

Last year, the U.S. aimed to cut off all revenue from Iran's oil export - the money that keeps the country running. The goal was regime change in Tehran.

Despite the escalating strain between the two countries, the U.S. envoy at the United Nations, Jonathan Cohen, said the Trump administration's aim is to get Tehran back to negotiations.