WASHINGTON — After the pre-dawn U.S. strike on a key airfield in Syria, Russia rushed to the defense of ally Bashar al-Assad while Syrian rebels warned that the United States must persist as civilians are in danger of retaliatory attacks from the Syrian leader.

Fifty-nine Tomahawks from two U.S. warships in the Mediterranean, the USS Ross and USS Porter, targeted Shayrat Airfield in Homs province at 4:40 a.m. local time. Defense officials reportedly used radar tracking to pinpoint the base as the originating location of the planes that dropped a neurotoxin on a town in Idlib province Tuesday.

The Syrian Observatory for Human Rights bumped up the death toll in the Khan Shaykhun sarin attack to “at least” 86, including 30 children and 20 women; the toll was expected to rise given the gravity of injuries.

Pentagon spokesman Capt. Jeff Davis said the missiles “targeted aircraft, hardened aircraft shelters, petroleum and logistical storage, ammunition supply bunkers, air defense systems, and radars.”

Defense officials informed Russia ahead of time about the planned airstrike time and location, citing their previous deconfliction agreement to improve flight safety after near-misses as the Russians flew missions with Assad forces against Assad’s opposition and the U.S. flew missions against ISIS. “U.S. military planners took precautions to minimize risk to Russian or Syrian personnel located at the airfield,” Davis said.

Russia’s foreign ministry, arguing that Assad doesn’t have chemical weapons, lashed out in a statement shortly after the strikes, calling it “not the first time that the U.S. chooses an irresponsible approach that aggravates problems the world is facing, and threatens international security.”

Russia further warned America of “abetting international terrorism and making it stronger,” ominously warning “new WMD attacks can be expected.”

“It is obvious that the cruise missile attack was prepared in advance. Any expert understands that Washington’s decision on air strikes predates the Idlib events, which simply served as a pretext for a show of force,” the statement added, also announcing the suspension of the memorandum of understanding on flight safety under which they received advanced notice of the strikes.

“It is regrettable that this is damaging Russian-U.S. relations, which are already in poor shape,” Russian Foreign Minister Sergey Lavrov said at a news conference in Uzbekistan today. “I hope these provocations will not produce irremediable results, although the media are citing joyful statements by former members of the Obama administration to the effect that Russian-U.S. cooperation looks utterly unrealistic after these strikes. I hope they will be brought to shame, although we will draw conclusions from this situation regarding the future of our relations with Washington.”

“As for possible victims among Russian servicemen, I have no information on this issue,” he added. “It appears that there were none.”

The Syrian regime’s official news agency, SANA, said nine were killed in the airbase strikes and “huge material damage” was inflicted. They released a statement from Assad’s office slamming the strikes as “an unjust and arrogant aggression.”

“Targeting an airport of a sovereign state by the U.S. is an outrageous act that clarifies in conclusive evidence once again what Syria has been saying that the succession of administrations of this regime does not change the deep policies of its entity which is represented by targeting states, subjugating peoples and the attempt to dominate the world,” the statement said.

Syria’s Army Command called the U.S. a “partner” of ISIS, which has been the target of daily airstrikes as the anti-Assad, anti-ISIS-and-Qaeda Syrian Democratic Forces close in on the ISIS capital, Raqqa.

The National Coalition of Syrian Revolution and Opposition Forces, which met with EU foreign policy chief Federica Mogherini in Brussels on Thursday to call for an international response to the gas attack, called for “the continuation of those operations” like the U.S. airstrikes “until the overthrow of the Assad regime.”

The coalition also called on Syrians to seize the moment and “unite and close ranks in one front politically, militarily” to “fight against terrorism in all its forms” while establishing “a pluralistic democratic system.”

In a statement, the Free Syrian Army called the strikes “a first step in the right direction towards the international community assuming its moral and legal responsibility to protect Syrian civilians and save them from the genocidal war that has been waged by the head of the regime and the war criminal Bashar al-Assad against the Syrians since 2011, free from any punishment for his actions, taking advantage of the reluctance of the former U.S. administration and the failure of the international community.”

“The factions of the Syrian revolution view this strike as a turning point in the fight against impunity and as part of the international war on terrorism,” the FSA added, acknowledging they now fear retaliation against civilians by Assad “and therefore we call on the United States and all countries friends of the Syrian people to stand clearly against the war criminals in the Syrian regime and put an end to their violations and bring them to trial for their crimes against the Syrians and all humanity.”