The U.S. ambassador to the United Nations said President Trump told her Saturday morning that if the Syrian regime uses poisonous gas again, "the United States is locked and loaded" to strike again. Nikki Haley relayed the message from Mr. Trump at an emergency meeting of the U.N. Security Council on Saturday.

"When our president draws a red line, our president enforces the red line," she said.

Haley said the message from the U.S., U.K. and French airstrikes overnight that "crippled Syria's chemical weapons program" was "crystal clear."

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"The United States of America will not allow the Assad regime to continue using chemical weapons," she said.

The U.N. Security Council -- deadlocked by an East-West divide -- met Saturday, with the U.S. U.K., and France making the case that the strikes were conducted in order to protect civilians and were proportionate and justified under the U.N. Charter and international law, CBS News' Pamela Falk reports from the U.N. Haley accused Russia of defending Syrian President Bashar Assad and failing to ensure that Syria's chemical weapons were destroyed as the Assad regime had pledged in 2013.

Her remarks came nearly a week after Syrian President Bashar Assad's alleged use of chemical weapons against civilians in a town outside Damascus -- and hours after the US., U.K. and France launched strikes against targets in Syria in response. On April 7, more than 40 civilians were killed in a suspected chemical attack in Douma. Syria has denied responsibility, but the U.S., France and Britain have said there is no doubt the Assad government was responsible.

On Friday night Eastern Time, Mr. Trump announced the joint airstrikes, which the Pentagon says "attacked the heart of the Syrian chemical weapons program." Lt. Gen. Kenneth McKenzie, the director of the Joint Chiefs of Staff at the Pentagon, said the strikes have been "a very serious blow."

On Saturday morning, Mr. Trump tweeted: "Mission Accomplished!"

Vice President Mike Pence, who is filling in for Mr. Trump at the Summit of the Americas in Lima, Peru, said Mr. Trump "made it clear to the world" that the United States "will not tolerate these chemical weapons."

Reaction pours in

The Arab League's chief has expressed regret and alarm at the latest developments in Syria following the launch of joint airstrikes to punish Assad. Secretary General Ahmed Aboul-Gheit told reporters on Saturday that all parties involved in the crisis, primarily the Syrian government, are responsible for the deterioration of the situation. The prohibited use of chemical weapons against civilians "shouldn't be accepted or tolerated," he said. adding that issue requires a sustainable political solution for the Syrian crisis.

Aboul-Gheit spoke from the city of Dammam in Saudi Arabia, where an Arab League summit is to take place Sunday.

Meanwhile, NATO said all 29 of its members in the alliance back the airstrikes on Syria as a consequence of the country conducting a suspected chemical attack against its civilians last weekend. NATO Secretary General Jens Stoltenberg said the strikes were about making sure that chemical weapons cannot be used with impunity. He noted that the three allies said it was "a very successful action" that significantly degraded the abilities of Syrian President Bashar Assad's forces to launch chemical attacks soon again.

Syrian TV called the attacks a "blatant violation of international law and shows contempt for international legitimacy." .

A former officer in Syria's chemical program said the strikes hit "parts of but not the heart" of the program. Adulsalam Abdulrazek said Saturday that the joint strikes were unlikely to curb the government's ability to produce or launch new attacks. Speaking from rebel-held northern Syria, Abdulrazek told The Associated Press there were an estimated 50 warehouses around Syria that stored chemical weapons before the program was dismantled in 2013. He said he believes those fixed storage facilities remain intact or were only slightly moved around.

He said Syria's chemical weapons program was only partially dismantled because Damascus didn't allow inspections of existing stockpiles and capabilities.

Russian President Vladimir Putin condemned Saturday's strikes as an "act of aggression" that will worsen the humanitarian catastrophe in Syria and have a "destructive influence on the entire system of international relations." He criticized Washington and its allies for attacking without waiting for inspectors from the international chemical weapons watchdog group to visit Douma, just outside Damascus.

The Russian military said its air defenses at two bases in Syria tracked the incoming missiles but didn't engage them.

Russian social media buzzed Saturday with angry nationalist comments blasting Putin for failing to protect his ally. But state TV focused on criticizing the West for acting on the basis of what Moscow called a faked chemical attack.

Iran's Supreme Leader Ayatollah Ali Khamenei said that the attack on Syria was a "crime" and declared the leaders of the U.S., France and the U.K. "criminals," according to Iran's state-run IRNA news agency. The Iranian Foreign Ministry strongly condemned the strikes and warned of unspecified consequences.

Turkey's president, meanwhile, said the airstrikes on Syrian targets were "correct" and showed the Syrian regime that such actions would not go "unanswered." Speaking Saturday in Istanbul, Turkish President Recep Tayyip Erdogan expressed his support of the joint American, British and French military operation but said more must be done to hold the Syrian regime accountable for the hundreds of thousands killed using conventional weapons.

"The people martyred by chemicals is a certain amount, but the people martyred by conventional weapons is much, much more," he said.