The United States started its military action against Syria's capital Damascus before daybreak Saturday as loud explosions were heard here with "red dots" seen flying from earth to the sky, reported Syrian state TV and Xinhua reporters in Damascus.

As loud explosions were heard across the capital, the Syrian air defense missiles were launched from Mount Qasioun, which overlooks the capital, with smoke rising from areas in Damascus, according to Xinhua reporters on the ground.

The air defense missiles looked like red dots flying from earth to targets in the sky.

The state TV also reported that the Syrian air defense system was reacting to the "U.S., French and British aggression on Syria."

U.S. Chairman of the Joint Chiefs of Staff Joseph Dunford said on Friday that the U.S. attack targeted multiple sites in Syria, including a research center, a chemical weapon storage facility and a facility in the second target.

The United States has accused Syria of using chlorine gas in an attack last week in the previously rebel-held Douma district near Damascus, pledging a military strike against the Syrian government forces' positions amid threats of retaliation from both the Syrian forces and Russia.