Iranian missiles hit two Iraqi bases hosting US troops amid rising tensions following US killing of Iran's Soleimani.

(CNN)Iran fired a number of missiles at two Iraqi bases housing US troops Wednesday in retaliation for the American strike that killed a top Iranian general last week.

The early morning attack presents President Donald Trump with the biggest test of his presidency to date.

A US official told CNN that there were no initial reports of any US casualties from the attack, but an assessment of the impact of the strikes is underway. Iraq's joint military command said there were no casualties among Iraqi military forces.

There is a growing belief among some administration officials that Iran's missiles intentionally missed areas populated by Americans when they targeted the two Iraqi bases, multiple administration officials said.

These officials floated the notion that Iran could have directed their missiles to hit areas that are populated by Americans, but intentionally did not.

Iraq did receive advance warning that the strike was coming and were able to take "necessary precautions," according to a statement from Iraq's Prime Minister Adil Abdul Mahdi.

White House aides had initially made plans for a possible address to the nation by Trump after the missile strikes, according to two officials, but a White House official said the President would not speak immediately. Trump tweeted later in the night that he would make a statement Wednesday morning.

"All is well!" Trump tweeted. "Missiles launched from Iran at two military bases located in Iraq. Assessment of casualties & damages taking place now. So far, so good! We have the most powerful and well equipped military anywhere in the world, by far! I will be making a statement tomorrow morning."

The attack comes days after the US killed top Iranian general Qasem Soleimani in an airstrike in the Iraqi capital of Baghdad. The administration had sought to cast that strike as an attempt to de-escalate tensions with Iran, but Tehran has described it as an "act of war" and "state terrorism."

In a televised address to Iran Wednesday, Supreme Leader Ayatollah Ali Khamenei said that the country gave the US "a slap in the face last night," in reference to the attacks.

He added that America had cast Soleimani as a "terrorist," which was "unjust and unfair."

The Islamic Revolutionary Guards Corps, an elite wing of the Iranian military, said in a statement that the attacks on Iraqi bases were "hard revenge" for the death of Soleimani. The IRGC said any country housing US troops could be subject to "hostile and aggressive acts" and called on American citizens to demand the government remove US troops from the region.

It warned the US: "If you repeat your wickedness or take any additional movements or make additional aggression, we will respond with more painful and crushing responses."