The U.S. is prepared to wipe out areas of Iran if the country decides to attack ‘anything American,' President Donald Trump threatened Tuesday morning on Twitter.

“Any attack by Iran on anything American will be met with great and overwhelming force,” Trump tweeted. “In some areas, overwhelming will mean obliteration. No more John Kerry & Obama!”

Trump’s remarks come after Iran mocked new sanctions the U.S. imposed Monday against the Islamic Republic’s supreme leader and other top officials. According to Iran, the sanctions closed the door on any diplomacy with the U.S., and President Hassan Rouhani accused the White House of being "afflicted by mental retardation.”

Tensions between the U.S. and Iran are escalating as the two countries exchange barbed words. The U.S. has blamed Iran for attacking two oil tankers near the Gulf of Oman on June 13, which Iran denies.

Iran shot down a U.S. surveillance drone June 20. The U.S. and Iran disagree over whether the drone was over international waters or was violating Iran’s airspace. Although Trump was then poised to launch a military strike against Iran, he claimed he canceled it because of the number of estimated casualties.

Trump withdrew the U.S. from the 2015 Joint Comprehensive Plan of Action, Iran’s nuclear deal, in spring 2018 and announced that sanctions against Iran would be reinstated. The Iran nuclear deal imposed limits on Iran’s nuclear program in exchange for relief from economic sanctions.

Iran has since accused the U.S. of waging an “economic war” against Iran.