WASHINGTON -- Pentagon spokesperson Dana White said Saturday the U.S. and its allies "successfully hit every target" in airstrikes in Syria overnight. The U.S., U.K. and France and U.K. launched the strikes Friday night Eastern Time in response to the Syrian regime's alleged use of chemical weapons last weekend. In total, the U.S. used 105 weapons against three targets.

"I can assure you we took every measure and precaution to strike only what we targeted and –– and we successfully hit every target," White told reporters Saturday.

White said the U.S. believes it has "significantly crippled" Syrian President Bashar Assad's ability to carry out a chemical weapons attack. White said the mission in Syria remains defeating the Islamic State of Iraq and Syria (ISIS), but the U.S. will not stand by while Assad attacks "innocent Syrian people."

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Later Saturday morning, the U.N. Security Council held an emergency session at Moscow's request in response to the airstrikes, CBS News' Pamela Falk reports from the United Nations. U.S. Ambassador to the U.N. Nikki Haley made the case for the strikes, saying the U.S. and allies acted "not as revenge, not as punishment, not as a symbolic show of force."

"We acted to deter the future use of chemical weapons by holding the Syrian regime responsible for its atrocities against humanity, she said.

"I spoke to the president this morning," Haley said, referring to Mr. Trump, "and he said if the Syrian regime uses this poisonous gas again, the United States is locked and loaded."

At the U.N. meeting, a Russian draft resolution condemning "aggression" against Syria by the U.S., France and U.K was defeated overwhelmingly. Only three votes at 15-nation Council were in favor, Falk reports.

France's Ambassador Francois Delattre said the U.K., U.S., and France will introduce a new resolution to establish an accountability mechanism for the perpetrators of the attacks. And U.N. Secretary General, Antonio Guterres, called on the Security Council to speak with one voice on chemical weapons use against civilians.

Lt. Gen. Kenneth McKenzie, the director of the Joint Staff at the Pentagon, told reporters earlier Saturday morning the initial assessment of the strikes against Syria is that the Defense Department accomplished its goals "without material interference" from Syrian defenses. The attempts from Syrian defenses were imprecise, in contrast to the U.S. mission, he said.

"We are confident that all of our missiles reached their targets," McKenzie emphasized, reiterating what White said.

McKenzie said, "As of right now, we are not aware of any civilian casualties," although they cannot be certain, given the defense launched by the Syrians.

Mr. Trump is claiming success.

"Mission Accomplished!" he tweeted Saturday morning, after addressing the nation the night before to announce the attacks.

Secretary of Defense James Mattis emphasized that the targets were infrastructure related to the Syrian regime's chemical weapons program, and that there are no plans at this time for further strikes.

But the president, in his address to the nation from the White House, declared that the U.S. is prepared to continue military intervention until Assad stops the use of chemical weapons.

"Establishing this deterrent is a vital national security interest of the United States," Mr. Trump said Friday night. "The combined American, British and French response to these atrocities will integrate all instruments of our national power — military, economic and diplomatic. We are prepared to sustain this response until the Syrian regime stops its use of prohibited chemical agents."

The U.S. Navy guided-missile cruiser USS Monterey fires a Tomahawk land attack missile April 14, 2018. U.S. Navy/Lt. j.g Matthew Daniels/Handout via HANDOUT / REUTERS

White agreed with Mr. Trump's assessment, even as the Pentagon leaves its options open about any future strikes.

"It was mission accomplished," she said. White insisted that, despite the U.S. intervention in attempting to stop Assad's alleged use of chemical weapons on his own people, the U.S. mission in Syria remains defeating ISIS.

"Our focus remains defeating ISIS. It is not to get involved in the Syrian civil war," she said.

Russia has said the strikes were a violation of the U.N. Charter and international law, CBS News' Falk reports. Russia also called them "an act of aggression" and warned that the airstrikes will "not be left without consequences." Russia said "all responsibility" rests with Washington, London and Paris.

On Saturday, Syrian state TV carried live images of hourslong street celebrations with people dancing and chanting in support of their government's "steadfastness" following the unprecedented joint airstrikes. The report showed people waving Syrian flags, alongside those of Iran and Russia -- the main allies of Syrian President Assad during years of the country's conflict -- in the face of what many called "limited" or even "failed" strikes designed to punish Assad for his alleged use of chemical weapons.

Syrian air defenses intercepted most of the incoming missiles, according to the report, which urged citizens not to believe other media reports "intentionally or unintentionally" exaggerating the results of the attack.

The Syrian army, meanwhile, declared the eastern suburbs of the capital Damascus "fully liberated" after the last group of gunmen left the town of Douma, the site of the alleged chemical attack last weekend. An army statement read by chief military spokesman Brig. Gen. Ali Mayhoub said Saturday that special units are clearing streets and squares of Douma from mines and explosives planted by rebels.

Douma is the largest town of the suburbs known as eastern Ghouta and its capture marks the biggest victory for President Assad's forces since the conflict began seven years ago. The army said that troops discovered weapons factories, arms depots, tunnels and food storage places.

For continuing coverage of the Syria strikes, watch CBSN in the video player at the top of this story.