The Free Syrian Army (FSO) welcomed US missile strikes against the government of President Bashar al-Assad early Friday and urged more attacks on regime forces.
For months, the US -led coalition spearheading the fight against the Islamic State group has conducted a delicate detente, fighting in northern Syria while also turning a watchful eye on Syrian forces and Russian jets targeting the terrorist group.
"We also consider this strike to be a first step in the right direction towards the worldwide community assuming its moral and legal responsibility to protect Syrian civilians and save them from the genocidal war since 2011", it added.
The Russian military said it would help Syria beef up its air defences after the USA strike on the Syrian air base.
Washington claims the base was used by the Syrian government to launch a chemical attack on civilians in Idlib province on Tuesday, where around 80 people were killed.
United States officials informed Russian forces ahead of the missile strikes and avoided hitting Russian personnel. Eastern time, 3:45 a.m.in Syria.
Russia expects Tillerson to explain Washington's stance when he visits Moscow next week, Interfax news agency cited a Russian Foreign Ministry spokeswoman as saying.
"The only reason why Bashar Assad is in power today is because of Russian Federation and Iran - certainly not because of Syrians", McCain said.
At the same time, the tension between Washington and Moscow created by the USA airstrike in Syria needs to be eased, quickly and carefully.
Assad's office said Syria would strike its enemies harder.
"To undermine Islamic State's abilities to pose as a threat to global security, the Trump administration must more aggressively work to deny [IS] territorial holdings", said Michael S. Smith II, a terrorism analyst. US warplanes frequently attack Islamic State militants in Syria and come close to Russian forces.
The U.S. airstrike "will help the war on IS because it shows seriousness from the Trump administration in dealing with IS and solving the crisis in Syria", he said. USA officials suggested Syria had violated the Chemical Weapons Convention and in doing so breached a 2013 Security Council resolution.
Secretary of State Rex Tillerson, who also was in Florida with Trump and is scheduled to go to Moscow next week, said he was disappointed but not surprised by the Russian reaction because it showed continued support for Assad.
The first direct U.S. attack on the Syrian government is retaliation for this week's chemical bomb attack on civilians. "And that's why the White House is obviously signaling that, notwithstanding the president's willingness to take military action, he is going to continue to be very skeptical about getting the United States deeply involved in a civil war for which there is no military solution". "But the decision over the nature of that outcome is not for President Trump to make alone".