— -- Syria and Russia on Friday slammed the United States for its airstrike against a Syrian air base, with Russia blasting the attack as an "act of aggression against a sovereign Syria."
Syrian President Bashar al-Assad's office said in a statement Friday that the U.S. "naively followed a false and lying propaganda campaign" that led it to "carry out this irresponsible recklessness."
“The presidency of the Arab Syrian republic asserts that what America carried out was an irresponsible act that only reflects shortsightedness, a narrow perspective and political and military blindness toward reality," the statement said.
The Syrian president's statement called the airstrike "a shameful act ... [that] clearly demonstrates, once again, what Syria has said and continues to say –- that changing administrations doesn’t change the deep policies of this government, namely, the targeting of countries, the subjugation of people and an attempt to dominate the world."
The Russian foreign ministry said it was calling for an urgent United Nations Security Council meeting over the airstrike.
Initial reports also stated that Russia suspended its air-safety hotline agreement with the U.S., which the two nations use to avoid collisions between their respective aircraft. But a senior military official on Friday disputed these reports, saying the air-safety hotline is still in operation.
Russia, a stalwart ally of the Syrian government, said the airstrike undermined the U.S. justification for having military personnel in Syria. U.S. military personnel in Syria advise and assist a coalition of forces fighting ISIS.
The Russian foreign ministry said in a statement that the presence of military personnel from the U.S. and other countries in Syria without either the permission of Syria's government "or a resolution of the U.N. Security Council is a gross, clear and in no way justified violation of international law."
"If before it was explained as a mission in the battle against terrorism, now it is a clear act of aggression against a sovereign Syria. The taking of these actions by the U.S. today yet further undermines Russo-American relations," the Russian statement said.
President Trump authorized the airstrike Thursday after blaming Syrian President Bashar al-Assad for a chemical attack Tuesday that killed at least 86 civilians. The U.S. launched 59 tomahawk missiles against the Syrian air base that U.S. officials say was the origin of the chemical weapons used in Tuesday's attack.
At least 86 civilians died from the attack on the town of Khan Sheikhoun on Tuesday, including an estimated 30 children, according to the Syrian Observatory for Human Rights.
After autopsies were conducted on victims brought to Turkish hospitals for treatment, Turkey's health ministry confirmed Thursday that the patients had been exposed to sarin gas, a banned nerve agent.
A U.S. official also said the symptoms exhibited by the victims pointed to sarin gas.
The U.S. official told ABC News that a Syrian military fixed-wing aircraft dropped the chemical weapons on what was an underground hospital run by an al-Qaeda affiliated rebel group formerly known as Al-Nusra Front.
Syria's government has denied carrying out the chemical weapons attack, and Russia has said that toxic agents were released when a Syrian airstrike hit a rebel chemical weapons arsenal and munitions factory.
Tuesday's attack is the latest atrocity in Syria's ruinous six-year war.
What started as a local protest movement in Syria’s southern city of Dara'a expanded into a full-fledged civil war by 2012. ISIS, which grew out of al-Qaeda in Iraq, took root in northern and eastern Syria in 2013 after seizing swaths of territory in neighboring Iraq. The jihadist group is fighting to overthrow Assad's regime and establish a caliphate.
The civil war has pulled in the United States, Russia, Iran and almost all of Syria's neighbors. It has become the largest humanitarian crisis since World War II, according to the U.N.
Russia, which launched its military operation in support of Syrian government forces in September 2015, has an estimated 4,000 troops in Syria and is Assad's key backer.
ABC News' Benjamin Gittleson, Luis Martinez, Kirit Radia, Patrick Reevell and Marcus Wilford contributed to this report.