President Trump on Friday night announced he has directed the U.S. military, in coordination with France and the United Kingdom, to conduct precision strikes in Syria, in response to the chemical weapons attack that left dozens dead on Sunday.

"A short time ago, I ordered the U.S. Armed Forces to launch precision strikes on targets associated with the chemical weapons capabilities of Syrian dictator, Bashar al-Assad," the president said from the White House.

"A combined operation with the armed forces of France and the United Kingdom is now under way," he continued.

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Mr. Trump claimed the U.S. is "prepared to sustain" a response to curtail Syria until the Syrian regime stops using chemical weapons on its citizens, meaning this might not be the last use of military capabilities in Syria.

"We are prepared to sustain this response until the Syrian regime stops its use of prohibited chemical agents," Mr. Trump said.

Secretary of Defense James Mattis emphasized that the strikes were "specifically designed" to target key infrastructure critical to the Syrian regime's chemical weapons program. As of 10 p.m. EST, Mattis said there were no reports of losses among U.S. military personnel. The Pentagon said this wave of air strikes is "over," but did not rule out the possibility of further strikes later. The Pentagon said the strikes took place at 9 p.m. EST.

Mr. Trump also called out Iran and Russia, saying Syria would not have been able to carry out such an action if Russia had been a responsible nation. Russia has pledged to retaliate if the U.S. strikes Syria. In 2014, then-Secretary of State John Kerry said all chemical weapons had been cleared from Syria, with the aid of Russia.

Syria air defences strike back after air strikes by U.S., British and French forces in Damascus, Syria in this still image obtained from video dated early April 14, 2018. SYRIA TV via Reuters TV MANDATORY CREDIT. SYRIA OUT. NO RESALES. NO ARCHIVE REUTERS TV / REUTERS

"I also have a message tonight for the two governments most responsible for supporting, equipping and financing the criminal Assad regime," Mr. Trump said. "To Iran and to Russia I ask: what kind of nations wants to be associated with the mass murder of innocent men, women and children? The nations of the world, can be judged by the friends they keep. No nation can succeed in the long run by promoting rogue states, brutal tyrants and murderous dictators."

"President Putin and his government promised the world that they would guarantee the elimination of Syria's chemical weapons," Mr. Trump continued. "Assad's recent attack and today's response are the direct result of Russia's failure to keep that promise. Russia must decide if it will continue down this dark path or if it will join with civilized nations as a force of stability and peace."

The president's announcement comes shortly after he said he hopes and intends to pull out of Syria " very soon," before this latest chemical attack.

Chairman of the Joint Chiefs Gen. Joseph Dunford said in a news conference Friday that the three target areas included a scientific research center located in Damascus, a chemical weapons storage facility west of Homs and a nearby storage facility with chemical weapons equipment and an "important" command post.

Dunford said the research center was used for development, production and testing of chemical and biological warfare technology. He explained the facility in Homs was the primary location of Syrian sarin and precursor production equipment. Mattis said it is time for all nations to "unite" to bring an end to the use of such weapons, calling on responsible nations to "condemn the Assad regime.

Ending the briefing with reporters, Mattis said he expects a "significant disinformation campaign" from those aligned with Syria, a not-so-thinly-veiled comment at Russia, which hours earlier claimed Britain had staged the chemical attack.

The president's announcement comes barely one year after he announced strikes in Syria following a separate chemical weapons attack.

"Clearly, the Assad regime did not get the message last year," Mattis said, insisting this latest attack struck that infrastructure "harder." Mattis claimed the U.S. used more than "double" the amount of weapon power it did in last April's attack on a Syrian air base.

The State Department announced its definitive conclusion Friday afternoon that the Syrian regime was responsible for the attack. Mattis said the U.S. verified the chemical attack Thursday.

The White House had kept a tight lid on the military action ahead of Friday night, and hours before the strikes were directed, said no final plans had been made. Shortly before Mr. Trump's announcement, Vice President Mike Pence, who is in South America, was hurriedly rushed back to his motorcade and hotel with no explanation, fueling speculation that something could be happening with Syria.

Pence called House Minority Leader Nancy Pelosi, D-Calif., to inform her of the strikes, CBS News' Rebecca Kaplan reports. Pence informed other key congressional leaders ahead of the strikes as well.

There are roughly 2,000 U.S. troops on the ground in Syria as of the last numbers the Pentagon released. But Mr. Trump insisted Friday night the U.S. does not intend to have a permanent presence in Syria.

"Increased engagement from our friends including Saudi Arabia, United Arab Emirates, Qatar, Egypt, and other can assure that Iran does not profit from the eradication of ISIS," the president said. "America does not seek an indefinite presence in Syria. Under no circumstances."

Mr. Trump described a very specific type of target that the U.S. would go after, which are Syria's chemical weapon capabilities. That could be everything from aircraft that dropped chemical weapons to the headquarters that control the forces that drop the chemical weapons, CBS News national security correspondent David Martin reports.

French President Emmanuel Macron, in a statement issued immediately after the strikes, said the "red line" France established in May 2017 "has been crossed."

Shortly after Mr. Trump's announcement, Britain's Prime Minister Theresa May announced she authorized her country's forces to conduct "precision strikes" with America and France against Syria in the wake of the chemical attack that left dozens injured this week.

"This persistent pattern of behavior must be stopped -- not just to protect innocent people in Syria from the horrific deaths and casualties caused by chemical weapons but also because we cannot allow the erosion of the international norm that prevents the use of these weapons," May said in a statement.

She added, "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."

CBS News' Justin Carissimo and Kylie Atwood contributed to this report.