U.S. President Donald Trump on Saturday threatened to hit 52 Iranian sites “very hard” if Iran attacks Americans or U.S. assets after a drone strike that killed Iranian military commander Qassem Soleimani.

The strike, that killed Iranian General Soleimani and Iranian-backed Iraqi militia leader Abu Mahdi al-Muhandis at Baghdad airport on Friday, has raised the specter of wider conflict in the Middle East.

Trump issued a threat to Iran on Twitter Trump said that the United States has “targeted 52 Iranian sites” and that some were “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!” Trump said, adding that the 52 targets represented the 52 Americans who were held hostage in Iran for 444 days after being seized at the U.S. Embassy in Tehran in November 1979 – an enduring sore spot in U.S.-Iranian relations.

Trump did not identify the sites. The Pentagon referred questions about the matter to the White House, which did not immediately respond to a request for comment.

Among the mourners in Iraq included many militiamen in uniform for whom Muhandis and Soleimani were heroes. They carried portraits of both men and plastered them on walls and armored personnel carriers in the procession. Chants of “Death to America” and “No No Israel” rang out.