Just minutes after Trump's Friday night address, large explosions were reported at sites near Damascus and in the countryside of Homs.

Susan Walsh / AP

The US and two European allies launched airstrikes against Syria overnight Friday in retaliation for a chemical weapons attack on a Damascus suburb that killed dozens of civilians.

Announcing the strike from the White House, President Donald Trump said the US was prepared to sustain its response, which was carried out in conjunction with the UK and France, “until the Syrian regime stops its use of prohibited chemical agents.” Trump singled out Russia and Iran as “most responsible for supporting, equipping, and financing the criminal Assad regime.” “Russia must decide if it will continue down this dark path or if it will join with civilized nations as a force for stability and peace,” Trump continued. “Hopefully, someday, we’ll get along with Russia and maybe even Iran, but maybe not.” One hour later, Defense Secretary James Mattis told reporters at the Pentagon that the military coalition had targeted three chemical weapons facilities operated by the Syrian regime of Bashar al-Assad. A spokesperson for the Free Syrian Army, however, claimed to BuzzFeed News that the number of sites that were struck was higher. Mattis said that there were no immediate plans for additional strikes, but warned that it depended on Syria’s response. “Right now, this is a one-time shot,” he said.

US Navy In this hand-out photo, the guided-missile cruiser USS Monterey (CG 61) fires a Tomahawk land attack on Friday.

Just minutes after Trump’s address, witnesses reported hearing large explosions in Damascus and in the countryside of Homs. The strikes targeted the Barzah Research and Development Center, near Damascus; the Him Shinsar chemical weapons storage facility; and the Him Shinsar chemical weapons bunker, west of Homs, the Pentagon said on Saturday. The Russian Embassy responded to the strikes in a statement, saying their “worst apprehensions have come true. Our warnings have been left unheard.” “A pre-designed scenario is being implemented,” the embassy added. “Again, we are being threatened. We warned that such actions will not be left without consequences.” The Russians did not elaborate on what those consequences might be. US military officials told reporters they could not say if they expected retaliation, but "we're ready for it." Mattis said there were no US losses in Friday’s strikes, and as of Saturday morning US officials said they were not aware of any civilian casualties. Unlike last year, the attack involved manned aircraft, which meant US and partners’ pilots were at risk of encountering Syrian air defenses, which have been bolstered by Russia. In recent months, Russia has reportedly increased the number of S-400 surface-to-air missile systems in western Syria. Alexander Zasypkin, the Russian ambassador to Lebanon, on Wednesday also warned that Russia would shoot down any missiles targeting Syria, “and even the sources from which the missiles were fired.” The US notified Russia that its aircraft were in Syrian airspace prior to the attack, using their usual military-to-military deconfliction line, Gen. Joe Dunford, the chair of the Joint Chiefs of Staff, told reporters at the Pentagon. But that's where the warnings ended, with US officials saying they gave no advanced notice of possible targets. UK Prime Minister Theresa May said in a statement that she had authorized military strikes after the Assad regime demonstrated a “pattern” of using chemical weapons on civilians. The UK, May said, had “sought every possible diplomatic channel” to resolve the crisis.

“So there is no practicable alternative to the use of force to degrade and deter the use of chemical weapons by the Syrian Regime,” she said. May added that the strikes were “not about intervening in a civil war,” but rather about sending “a clear signal to anyone else who believes they can use chemical weapons with impunity.”

The Prime Minister @theresa_may has made a statement on Syria: https://t.co/bBfYyowUIo

French President Emmanuel Macron said in a statement that his country’s “red line” had been crossed by the April 7 attack, and as a result, his country joined in the strikes. News of the strikes came at the end of a day in which legal developments involving the US special counsel investigation of Russian meddling in the 2016 election dominated the news. Trump pardoned former Bush administration aide Scooter Libby in what many saw as a possible effort to signal to potential witnesses that they don't have to fear a perjury charge. News then broke that the president's lawyer, Michael Cohen, was the subject of a criminal investigation, and, subsequently, had been the go-between in a $1.6 million payoff by a Republican fundraiser to his mistress. The strikes also came during a week that saw the FBI raid of Trump's personal lawyer's office and the release of excerpts from former FBI director James Comey's book, both reportedly enraging the president.

Vice President Mike Pence left an event in Peru early so he could give advance notice of the strikes to congressional leaders, according to the White House press pool. Shortly before Trump’s announcement, Pence made calls to House Speaker Paul Ryan, Senate Majority Leader Mitch McConnell, and House Minority Leader Nancy Pelosi. Trump's decision to launch the strikes followed days of deliberations with his military leaders and national security advisers that pitted the Pentagon's concerns about an escalating conflict and Trump and his new national security adviser John Bolton's desire for a broader, more muscular response. Mattis even signaled what he was advising the president while testifying on Capitol Hill on Thursday, telling lawmakers his biggest concern was "how do we keep this from escalating out of control, if you get my drift on that." Democrats in Congress were quick to rebuke Trump's action, arguing that while the suspected chemical weapons attack was horrific, the president lacked the authority to unilaterally order the airstrikes and threatened to draw the US deeper into the Syrian conflict. “One night of airstrikes is not a substitute for a clear, comprehensive Syria strategy,” Pelosi said in a statement. Democratic Sen. Tim Kaine, a member of the Senate Foreign Relations and Armed Services committees, also said Trump’s decision to launch airstrikes without Congressional approval “is illegal and – absent a broader strategy – it’s reckless.” Republican Rep. Thomas Massie of Kentucky also expressed opposition to the move, saying on Twitter, “I haven’t read France’s or Britain’s 'Constitution,' but I’ve read ours and no where in it is Presidential authority to strike Syria.”

Hassan Ammar / AP Skies light up with surface-to-air missile fire early Saturday in Damascus, Syria.