A new round of U.S. economic sanctions targeting Iran’s Supreme Leader Ayatollah Ali Khamenei and other top officials meant a “permanent closure” of diplomacy now exists between Tehran and Washington, the Islamic Republic warned Tuesday.

U.S. President Donald Trump signed an executive order imposing the sanctions on Monday, taking a dramatic and unprecedented step to increase pressure on Iran after Tehran’s downing of an American drone last week.

“We do not seek conflict with Iran or any other country,” Trump told reporters in the Oval Office at the signing ceremony. “I can only tell you we cannot ever let Iran have a nuclear weapon.”

Sanctions were also imposed on eight senior commanders of Navy, Aerospace, and Ground Forces of the Islamic Revolutionary Guards Corps (IRGC), the U.S. Treasury Department said.

Washington said it would also impose sanctions on Iran’s Foreign Minister Mohammad Javad Zarif later this week, sparking an immediate response from Iran.

“Imposing useless sanctions on Iran’s Supreme Leader (Ayatollah Ali Khamenei) and the commander of Iran’s diplomacy (Foreign Minister Mohammad Javad Zarif) is the permanent closure of the path of diplomacy,” Foreign Ministry spokesman Abbas Mousavi said in a tweet.

.@realDonaldTrump is 100% right that the US military has no business in the Persian Gulf. Removal of its forces is fully in line with interests of US and the world. But it’s now clear that the #B_Team is not concerned with US interests—they despise diplomacy, and thirst for war. — Javad Zarif (@JZarif) June 24, 2019

“Trump’s desperate administration is destroying the established international mechanisms for maintaining world peace and security.”

As the diplomatic spat between the two nations rolls on, U.S. Secretary of State Mike Pompeo continues to tour the Middle East to build a “global coalition” against Iran.

Before leaving the U.S. capital for the Middle East, Pompeo told reporters that he would talk with the two U.S. Sunni Arab allies Saudi Arabia and the UAE.