President Donald Trump said he was ready to make strikes on 52 locations in Iran, including Iranian cultural sites and sites he deemed important to the country, if Tehran continued to threaten the United States.

Trump tweeted the threat on Saturday night after Iran’s leadership vowed to take revenge for the U.S.’s assassination of Maj. Gen. Qassem Soleimani, the commander of Iran’s elite Quds Force and one of the most powerful military figures in the Middle East.

“Iran is talking very boldly about targeting certain USA assets as revenge for our ridding the world of their terrorist leader who had just killed an American, & badly wounded many others, not to mention all of the people he had killed over his lifetime,” Trump wrote.

“Let this serve as a WARNING,” the president added, “that if Iran strikes any Americans, or American assets, we have ... targeted 52 Iranian sites (representing the 52 American hostages taken by Iran many years ago), some at a very high level & important to Iran & the Iranian culture, and those targets, and Iran itself, WILL BE HIT VERY FAST AND VERY HARD. The USA wants no more threats!”

On Nov. 4, 1979, armed Iranian students aligned with Iran’s government took 52 Americans hostage at the U.S. Embassy in Tehran during Iran’s Islamic Revolution. The U.S. diplomats spent 444 days in captivity until they were released on Jan. 20, 1981.

Iran is talking very boldly about targeting certain USA assets as revenge for our ridding the world of their terrorist leader who had just killed an American, & badly wounded many others, not to mention all of the people he had killed over his lifetime, including recently.... — Donald J. Trump (@realDonaldTrump) January 4, 2020

....hundreds of Iranian protesters. He was already attacking our Embassy, and preparing for additional hits in other locations. Iran has been nothing but problems for many years. Let this serve as a WARNING that if Iran strikes any Americans, or American assets, we have..... — Donald J. Trump (@realDonaldTrump) January 4, 2020

....targeted 52 Iranian sites (representing the 52 American hostages taken by Iran many years ago), some at a very high level & important to Iran & the Iranian culture, and those targets, and Iran itself, WILL BE HIT VERY FAST AND VERY HARD. The USA wants no more threats! — Donald J. Trump (@realDonaldTrump) January 4, 2020

Iran’s supreme leader, Ayatollah Ali Khamenei, and its Supreme National Security Council have vowed to take “forceful revenge” for the death of Soleimani, who was revered by many Iran.

The council said it had reached a decision on how to respond to the U.S.’s aggression, though the details or the extent of that reaction is still unknown.

While Trump said he ordered the airstrike killing to prevent Soleimani from directing attacks on Americans, experts worry that targeting such a high-level Iranian military figure in Iraq soil destabilizes the U.S. military’s foothold in the region.

Iran is linked to tens of thousands of armed proxies and militias, many of whom were empowered by Soleimani’s leadership, in both Iraq and Syria, as well as neighboring countries.

In anticipation of Iran’s response, Trump ordered the deployment of 3,000 more troops to the Mideast to act as reinforcements.

The United Nations Security Council considers it a war crime for any military to intentionally target or destroy sites of cultural heritage, including museums and religious and archaeological sites.

After the Pentagon claimed responsibility for Soleimani’s assassination, Trump on Friday said he had “deep respect” for Iranians and praised their “incredible heritage.”

The White House did not immediately respond to a HuffPost request for comment.

CORRECTION: An earlier version of this article said the American hostages in Iran were released on Jan. 29, 1981; it was on Jan. 20, 1981.