Damascus sky lights up with service to air missile fire as the U.S. launches an attack on Syria targeting different parts of the Syrian capital Damascus, Syria, early Saturday, April 14, 2018.

President Donald Trump announced Friday night that he ordered the U.S. military to conduct precision missile strikes against the Syrian government, in retaliation for a chemical attack executed against its citizens.

The order — carried out in conjunction with French and British allies — marked a dramatic reversal for Trump. As recently as last week, had been saying that he wanted the U.S. to withdraw its forces from Syria. Then, days after a suspected chemical attack by Syrian forces on rebels, Trump warned over Twitter that missile strikes would be coming.

In a speech from the White House, Trump declared that the U.S.-led coalition's intent was to "establish a strong deterrent against the production, spread, and use of chemical weapons. Establishing this deterrent is a vital national security interest of the United States."

Although Trump has indicated his unwillingness to stay in Syria long-term, the president added that "we are prepared to sustain this response until the Syrian regime stops its use of prohibited chemical agents."

During Friday's speech, Trump noted that the strike was underway, but did not give further details of the targets or the military assets used. There were initial indications the strikes could occur over days, but officials at a Pentagon briefing later Friday said that the current wave of attacks was over.

Defense Secretary James Mattis, in a later briefing from the Pentagon, said Trump ordered the strikes to destroy Syria's chemical weapons development infrastructure.

Read more: White House releases the U.S. assessment of alleged chemical attack in Syria

There were reports of Syrian air defense forces firing back, but no immediate indications that U.S. planes were struck.

Trump used the address to also directly call out Russia and Iran, which back the regime of Syrian President Bashar Assad.

"To Iran and to Russia, I ask: What kind of a nation wants to be associated with the mass murder of innocent men, women and children?" Trump said. "Hopefully someday we will get along with Russia, and maybe even Iran. But maybe not."

Russia responded over Twitter, with a statement from its ambassador to the U.S., Anatoly Antonov.

"We warned that such actions will not be left without consequences," the statement said. "All responsibility for them rests with Washington, London and Paris."

RUSSIA TWEET

The Syria assault generated mixed reviews on Capitol Hill. Sen. Tim Kaine, D-Va., denounced the attack. "We need to stop giving presidents a blank check to wage war," he tweeted. "Today it's Syria, but what's going to stop him from bombing Iran or North Korea next?"

Separately, House Minority Leader Nancy Pelosi demanded Trump seek Congressional authorization, as well as a clear strategy for an endgame.

PELOSI TWEET

On the other hand, Sen. John McCain, R-Ariz., lauded the strikes, but called for Trump to draw up a more comprehensive plan for the region.

"Airstrikes disconnected from a broader strategy may be necessary, but they alone will not achieve U.S. objectives in the Middle East," McCain said in a statement. Earlier this week, McCain, the Senate Armed Forces Committee chairman, said Trump's talk of withdrawing from Syria had emboldened Assad to launch the alleged chemical attack.

The U.K. emphasized that the strikes were specifically targeted against Syria's purported chemical-weapons program.

"Our action is proportionate, specifically aimed at degrading the regime's ability to use chemical weapons and deterring further such appalling acts," said a statement from Britain's Royal Air Force. "It is therefore focused on regime facilities linked to the production and use of chemical weapons."

British Prime Minister Theresa May also issued a statement about the strikes.

"This is not about intervening in a civil war. It is not about regime change. It is about a limited and targeted strike that does not further escalate tensions in the region and that does everything possible to prevent civilian casualties," she said in a statement.