American military action against a Syria-government airfield late Thursday will do significant damage to relations between Russia and the U.S., according to the Kremlin quoted by the Interfax news agency.

The missiles targeted the Shayrat Airfield near Homs, and were in response to a Tuesday chemical weapons attack. Officially announcing the strike, President Donald Trump said that the targeted airfield had launched the chemical attack on a rebel-held area, and he called on other nations to oppose Syria’s embattled leader.

The Russian response on Friday morning claimed that the strikes violated international law. The Russian news agency Interfax reported comments from the Kremlin which said the strikes had happened under an “invented pretext”.

A quote from Kremlin spokesman Dmitry Peskov also said that President Vladimir Putin believed the U.S. attacks on Syria showed aggression against a sovereign state.

—CNBC’s Everett Rosenfeld contributed to this report.