President Donald Trump on Monday issued an executive order imposing new sanctions on Iran, including on Ayatollah Ali Khamenei, the country’s supreme leader.

The latest sanctions come as tensions rapidly increase between Washington and Tehran. The U.S. blamed Iran for recent attacks on tankers passing through the Strait of Hormuz, and Iran downed a U.S. drone last week. Tehran also said it would resume enriching uranium as it distances itself from the nuclear agreement, which the U.S. exited in May 2018. Last week, the U.S. also launched cyberattacks on Iran, according to the New York Times, and Trump called off military strikes minutes before they were set to reach their targets.

Trump, in remarks from the Oval Office, described the measures as “hard hitting,” adding that they follow “a series of aggressive behaviors by the Iranian regime in recent weeks.” Khamenei is ultimately responsible for Iran’s behavior, Trump said. “The assets of Ayatollah Khamenei and his office will not be spared from the sanctions,” he said.

Iran responded Tuesday by saying the path to diplomacy with the U.S. has “permanently closed,” and President Hassan Rouhani said the White House was “afflicted with mental disabilities,” while everyday Iranians mocked the move, according to the New York Times. Trump replied by saying he’ll use “overwhelming force” if Iran attacks U.S. interests.

In addition to designating the country’s supreme leader, the U.S. executive order also authorizes sanctions on anyone appointed directly by Khamenei or one of his appointees to a state position, the head of any state-owned entity, or board members or senior executive officers of Iranian entities. 

These measures build on the U.S. “maximum pressure” campaign against Iran that includes efforts to reduce Iranian crude oil exports to zero. Recently, the U.S. imposed sanctions on Iran’s largest petrochemical holding group, Persian Gulf Petrochemical Industry Co. (PGPIC) and its network of 39 subsidiaries and foreign-based sales agents. 

Much of Iran’s economy is already under sanctions, however: Secretary of State Mike Pompeo told reporters Sunday that “80-plus percent” of the economy is sanctioned. Heavy use of sanctions, especially on Iran, is spurring the development of mechanisms for trade that don’t rely on U.S. currency, The Wall Street Journal reported in May.