President Donald Trump says the United States has “targeted 52 Iranian sites” for attack if Iran takes action against “any Americans, or American assets” after the U.S. military killed Iranian military commander Qassem Soleimani on Thursday in Iraq.

The Saturday evening string of tweets comes on the same day that the White House formally notified Congress two days after the military action. Iran has vowed "harsh retaliation" for the U.S. airstrike, which was ordered by Trump and carried out near Baghdad International Airport.

In the tweets, the president said: “Let this serve as a WARNING 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 Pentagon plans to deploy close to 3,000 more troops to the Middle East in response to the friction, but Trump said he is not looking to go to war with Iran.