U.S. President Donald Trump announced on Friday evening that he has ordered the launch of airstrikes, along with the United Kingdom and France, on Syria in order to target the “criminal” regime of Syrian President Bashar Assad for his purported use of chemical weapons on civilians.

“A short time ago, I ordered the United States armed forces to launch precision strikes on targets associated with the chemical-weapons capabilities of Syrian dictator Bashar al-Assad,” Trump said in an address to America on Friday night.

He noted that the strikes, in coordination with the United Kingdom and France, are 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.”

U.K. Prime Minister Theresa May said that “the speed with which we are acting is essential in co-operating with our partners to alleviate further humanitarian suffering and to maintain the vital security of our operations.”

Similarly, French President Emmanuel Macron said “we can not tolerate the trivialization of the use of chemical weapons, which is an immediate danger for the Syrian people and for our collective security.”

The chemical-weapons attack in Syria on April 7 in the city of Douma in eastern Ghouta is suspected of killing dozens of people, including children. More than 500,000 people are estimated to have died so far in the seven-year civil war in Syria.

In his speech, Trump also warned both Russia and Iran, which have worked closely to support the Assad regime over the past several years, that they must decide if they want to continue to support the “mass murder of innocent men, women and children.”

“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,” he said.

The latest strikes comes nearly a year after Trump launched a more limited airstrike against the Assad regime for its chemical-weapons use. While last year’s strikes seemed to firm up Trump’s position that chemical weapons remain unacceptable, many criticized the president for lacking a comprehensive strategy in Syria to ensure that they would not be used again.

“Clearly, the Assad regime did not get the message last year,” Defense Secretary James Mattis said in a briefing at the Pentagon. “This time with our allies, we have struck harder.”

Trump said the United States was prepared to “sustain” pressure on Assad until he ends the use of chemical weapons. It was not immediately clear though if there would be further military action; however, according to CNN, a senior administration official said that “this isn’t over.”

“What you’ve seen tonight is not the end of the U.S. response. They have built a lot of flexibility into the plan to allow for further strikes based on what they’ve hit tonight,” the administration official said.

Last weekend, Israel purportedly also launched airstrikes in Syria, targeting its T-4 air base near Homs most likely as part of an ongoing campaign to target Iranian and its terror proxy Hezbollah’s assets in Syria. That airstrike killed at least 14 people, including several Iranian soldiers.