United States President Donald Trump on Tuesday threatened Iran with “obliteration” and said an attack on “anything American will be met with great and overwhelming force.”

“....Iran’s very ignorant and insulting statement, put out today, only shows that they do not understand reality,” Trump said in a tweet. “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!”

Earlier in the day, Iranian President Hassan Rouhani described the White House as “mentally retarded”, an insult Iran has used in the past for Trump. He dismissed the “hard-hitting” financial sanctions imposed on its Supreme Leader Ayatollah Ali Khamenei. Rouhani said that sanctions against Khamenei would fail because he had no assets abroad, and called the latest round of sanctions a sign of US desperation.

The sanctions are aimed at cutting off Iranian leadership’s access to financial resources, and barring them from using the United States’ financial system or having access to assets in America, according to Reuters.

“Iran leadership doesn’t understand the words “nice” or “compassion,” they never have,” Trump said in another tweet. “Sadly, the thing they do understand is Strength and Power, and the USA is by far the most powerful Military Force in the world, with 1.5 Trillion Dollars invested over the last two years alone.”

Trump said “the wonderful Iranian people” are suffering for no reason. “Their leadership spends all of its money on Terror, and little on anything else,” he claimed in another tweet.

Tension between both the countries have continued escalating since last week, after Iran shot down an American spy drone over the Strait of Hormuz. While Tehran claimed the drone violated its airspace, the US maintained it was shot down over international waters. Trump had also pulled back from plans to retaliate with military strikes on Iranian targets, saying the response – and the collateral damage – would not be proportionate.

The incident came at a time when the United States accused Iran of attacking two of its oil tankers in the Gulf of Oman on June 13. Hormozgan borders the Strait of Hormuz, where the tankers were located. The US military has also accused Iran of firing a missile at a drone that had responded to the explosions. In May, Washington had alleged Tehran had orchestrated a similar attack in which four tankers in the same area were damaged.