On Thursday night, U.S. warships launched 59 Tomahawk cruise missiles at an Al Shayrat airbase, controlled by the Syrian government.
President Donald Trump ordered the strike after a chemical weapons attack killed more than 70 civilians in the Syrian province of Idlib on Wednesday.
Moscow has already abandoned its safety cooperation with the U.S. air Force, and called for a UN Security Council meeting to discuss the situation.
Russian officials have responded to the strike in various ways.
Prime Minister Dmitry Medvedev claimed that the Trump administration has demonstrated "its lack of originality and its dependence on the Washington establishment." He also indicated that Trump went back on his campaign rhetoric, where he emphasized the importance of a joint fight against the Islamic State, preferring it to a "furious fight with the legitimate government of Syria." Medvedev also criticized Trump for not informing the U.S. Congress about the military operation, which approached "the verge of a military conflict with Russia."
The Russian Foreign Ministry issued a statement calling the strike an "act of aggression against a sovereign state," arguing that the mere presence of American forces on Syrian soil without an invitation from Syrian government or a UN Security Council mandate is itself a violation of international law.
"There is no doubt that this military action by the U.S. is an attempt to divert attention from the situation in Mosul," Russian defense officials said, pointing to “hundreds of civilian casualties and an escalating humanitarian disaster.”
Vyacheslav Volodin, the chairman of the State Duma, also called the strike an act of "aggression" against a sovereign state, recalling that the Bush administration previously used chemical weapons to justify the U.S. invasion of Iraq. “The role of the world policeman, especially one that ignores international law, is fraught [with consequences]," he said, accusing the White House of acting “under completely false pretenses.”
Andrei Kolesnikov, a senior associate at the Carnegie Moscow Center, indicated that the strike eliminated the chances for a potential U.S.-Russian rapprochement.
"And here is the result," Kolesnikov told the RBC news outlet. "Trump is no longer 'our man. And because of that, the frustration of the Russian side is even stronger than it might have been under a hypothetical President Hillary Clinton. The head of the American state, upon whom such hopes were placed, practically betrayed our interests."
Konstantin Kosachev, the chair of the Federation Council's Foreign Affairs Committee, said the U.S. airstrikes were meant only ony “cement with gunpowder the previously stated assertion that Assad is responsible for the chemical attack in Idlib."
Kosachev's colleague, senator Alexei Pushkov, called the strikes "the political revanche of Obama, Clinton and McCain" aimed against U.S.-Russian cooperation.
Leonid Slutski, the chairman of the State Duma's Committee on International Affairs, recalled Colin Powell's speech at the UN, where he presented "the infamous vial that served as the basis for invading Iraq."
"As always, America applies double standards to its actions by exerting aggression against government positions in Syria without any tangible evidence [of war crimes]," he told the TASS news agency. "While turning a blind eye to the use of chemical weapons by terrorists in Iraqi Mosul several weeks before,” he then added.
Finally, Vladimir Zhirinovsky, a long-serving Duma deputy and colorful nationalist leader, advocated sending Russia's Black Sea Fleet to help the Assad regime protect itself, also supplying additional S-300 and S-400 missile-defense systems.
"This is direct aggression by the U.S. against Syria," he said. "No one invited them. Syria has the right to retaliate."