Escalation of tensions between the United States and Iran reached a new level on Saturday as President Donald Trump threatened to strike 52 targets in Iran if any American or any U.S. assets are attacked by the Islamic Republic.

Trump tweeted that Iran "is talking very boldly about targeting certain USA assets", after the United States killed Qassem Soleimani, Iran’s top military and intelligence officer in the Middle East.

Trump said 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 after being seized at the U.S. embassy in Tehran in 1979.

The U.S. president again reiterated that Soleimani not only was responsible for killing Americans, but also “hundreds” of Iranian protesters.

Trump’s tweets and warning came as new rocket and mortar attacks threatened U.S. soldiers and personnel in Baghdad and at an air base north of the Iraqi capital. Pro-Iran militia also warned Iraqi troops not to protect American assets in the country.

Analysts point out that the unexpected drone attack in the early hours of January 3 that killed Soleimani can be a sign that Donald Trump is ready to escalate the conflict if threats from Iran and its proxies persist.