President Trump on Saturday touted the “perfectly executed strike” against the Assad regime in Syria, thanking France and Britain for joining the US-led assault before declaring “Mission Accomplished!”

The three countries launched military strikes overnight Friday in Syria to punish President Bashar Assad for an apparent chemical attack against civilians and to deter him from doing it again.

“A perfectly executed strike last night. Thank you to France and the United Kingdom for their wisdom and the power of their fine Military. Could not have had a better result. Mission Accomplished!,” Trump tweeted.

Pentagon officials said the attacks targeted the heart of Assad's programs to develop and produce chemical weapons.

Syrian television reported that Syria's air defenses, which are substantial, responded to the attack. Syrians poured into the streets for defiant demonstrations of their national pride.

Defense Secretary Jim Mattis said there were no reports of U.S. losses in what he described as a heavy but carefully limited assault.

Trump said earlier this weekend that the U.S. is prepared to sustain economic, diplomatic and military pressure on Assad until he ends what the president called a criminal pattern of killing his own people with internationally banned chemical weapons.

“So proud of our great Military which will soon be, after the spending of billions of fully approved dollars, the finest that our Country has ever had,” Trump also tweeted Saturday. “There won’t be anything, or anyone, even close!

The allied attack set off a fierce international debate about whether it was justified.

On Saturday, Putin reaffirmed Russia's view that a purported chemical attack in the Syrian town of Douma that prompted the strike was a fake. Putin added that Russian military experts who inspected Douma found no trace of the attack. He criticized the U.S. and its allies for launching the strike without waiting for inspectors from the international chemical weapons watchdog to visit the area.

The Syria attack drew support from the European Union, Germany, Israel and other allies while British Prime Minister Theresa May said reports indicate the Syrian government used a barrel bomb to deliver the chemicals used in an attack on Douma. She said the use of force was "right and legal" in this case.

Mattis said the assault was a "one-time shot," so long as Assad does not repeat his use of chemical weapons. The strikes were carried out by manned aircraft and from ships that launched cruise missiles from the Mediterranean Sea.

Mattis disclosed that the U.S. had not yet confirmed that the most recent suspected Syrian chemical weapons attack, on April 7 in the Damascus suburb of Douma, included the use of sarin gas. He said at least one chemical was used — chlorine, which also has legitimate industrial uses and had not previously triggered a U.S. military response.

Trump chastised Syria's two main allies, Russia and Iran, for their roles in supporting "murderous dictators," and noted that Russian President Vladimir Putin had guaranteed a 2013 international agreement for Assad to get rid of all of his chemical weapons. He called on Moscow to change course and join the West in seeking a more responsible regime in Damascus.

The U.S. missile strike a year ago, which targeted the airfield from where Syrian aircraft had launched their gas attack, was meant to deter Assad from further use of chemical weapons. Since that did not work, a more intense attack would aim to degrade his ability to carry out further such attacks, and would try to do this by hitting Syrian aircraft, military depots and chemical facilities, among other things.

The strikes that hit early Saturday in Syria came hours before inspectors from the Organization for the Prohibition of Chemical Weapons were set to arrive to inspect the site of the apparent attack.

The Associated Press contributed to this report.