By Zachary Cohen and Kevin Liptak, CNN
President Donald Trump announced on Friday he ordered strikes on the Syrian regime's chemical weapons facilities in coordination with France and the United Kingdom in response to a chemical weapons attack last weekend.
"I ordered the United States armed forces to launch precision strikes on targets associated with the chemical weapon capabilities of Syrian dictator of Bashar al-Assad," Trump said from the White House Diplomatic Reception Room.
Witnesses told CNN that they heard explosions in the capital city of Damascus and that they began while Trump was making his address.
US aircraft -- including B-1 bombers -- and ships were used in the attack, according to multiple US defense officials.
At least one US Navy warship based in the Red Sea participated in today's strikes, according to two US military officials.
Defense Secretary James Mattis said the US specifically targeted the Syrian regime's chemical weapons program.
"We also selected targets that would minimize the risks to innocent civilians," Mattis said.
"Right now this is a one-time shot and I believe that it sent a very strong message to dissuade (Assad), to deter him from doing this again," he added.
The targets included a scientific research center located in the greater Damascus area.
Mattis said, "This military facility was a Syrian center for the research, development, production, and testing of chemical and biological warfare technology."
The second target was a chemical weapons storage facility west of Homs, which Mattis said "was the primary location of Syrian Sarin and precursor production equipment."
Mattis said the third target "was in the vicinity of the second target" and "contained both a chemical weapons equipment storage facility and an important command post."
Trump said that he decided to take action because last weekend's action by Bashar Al-Assad "was a significant attack against his own people," and "not the actions of a man, they are crimes of a monster instead."
Trump said the strikes were in coordination with France and the United Kingdom, adding that the purpose of the campaign is to "establish a strong deterrent against the production, spread and use of chemical weapons."
"The combined American, British and French response to these atrocities will integrate all instruments of our national power: military, economic and diplomatic," Trump said.
UK Prime Minister Theresa May said in a statement that she "authorized British armed forces to conduct co-ordinated and targeted strikes to degrade the Syrian Regime's chemical weapons capability and deter their use."
"The UK element of the carefully coordinated joint action was contributed by four Royal Air Force Tornado GR4s," a statement from the UK Ministry of Defense said. "They launched Storm Shadow missiles at a military facility -- a former missile base -- some fifteen miles west of Homs, where the regime is assessed to keep chemical weapon precursors stockpiled in breach of Syria's obligations under the Chemical Weapons Convention."
Trump indicated the strikes would continue until the Syrian regime's use of chemical weapons ends.
"We are prepared to sustain this response until the Syrian regime stops its use of prohibited chemical agents," Trump said.
Two US officials said attacks could continue beyond tonight, with a senior administration official saying "this isn't over."
The senior administration official said, "What you've seen tonight is not the end of the US response. They have built a lot of flexibility into the plan to allow for further strikes based on what they've hit tonight."
A US official says a big concern is how much more sophisticated Russia's capabilities are now compared to last year. The source says they are 'significantly enhanced' in terms of anti-strike and anti-aircraft capabilities.
Part of the calculation this week has also been gaming out how Russia will respond. "We are watching what Russians do in the next 24 hours," the official said, adding that there will be intelligence collection to see what Russians are up to in the wake of the strikes, such as turning on their systems or talking about retaliating.
Chairman of the Joint Chiefs, General Joseph Dunford, said the US "specifically identified" targets to "mitigate the risk of Russian forces being involved" and that the normal deconfliction line was used in the run up to the strike to ensure clearance of airspace.
"We used the normal deconfliction channel to deconflict airspace, we did not coordinate targets," Dunford said.
The President also insisted that the US would not remain engaged in Syria forever under any circumstances. He has previously told his national security team he wants US troops to exit Syria within six months.
"America does not seek an indefinite presence in Syria," Trump said from the White House. "As other nations step up their contributions we look forward to the day we can bring our warriors home."
Trump told the nation in his address the US "cannot purge the world of evil or act everywhere there is tyranny."
And he described the Middle East as a "troubled place."
"We will try to make it better but it is a troubled place," Trump said. "The US will be a partner and a friend. But the fate of the region lies in the hands of its own people."
He criticized Russia's support of the Syrian regime saying "Russia must decide if it will continue down this dark path."
Trump also called out Russia's promise in 2013 that they would guarantee the elimination of Syria's chemical weapons.
Mattis said that Friday's attack used "double the amount of weapons" compared to the April 2017 strike.