The Pentagon released details on the U.S. missile strike against Syria on Thursday night, calling it “a proportional response” to the chemical attack officials say was carried out by Syrian President Bashar Assad.

“At the direction of the president,” U.S. forces launched 59 Tomahawk missiles from the destroyers USS Porter and USS Ross in the Eastern Mediterranean Sea, Pentagon spokesman Jeff Davis said in a statement, including footage of missiles being launched from the Navy warships.

The strike, which began shortly before 9 p.m. in Washington, or before 5 a.m. in Syria, targeted the Shayrat Air Base. It was a response to Tuesday's chemical attack, Davis said.

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U.S. officials said the airfield held chemical weapons and aircraft Syrian forces used in this week's attack that killed civilian men, women and children.

The Tomahawk missiles targeted “aircraft, hardened aircraft shelters, petroleum and logistical storage, ammunition supply bunkers, air defense systems, and radars,” according to the Pentagon written statement.

“As always, the U.S. took extraordinary measures to avoid civilian casualties and to comply with the Law of Armed Conflict. Every precaution was taken to execute this strike with minimal risk to personnel at the airfield."

Davis also said that U.S. officials notified Russian forces in advance of the strike and took precautions to minimize risk to Russian or Syrian personnel located at the airfield.

“The strike was a proportional response to Assad's heinous act,” Davis said. “The strike was intended to deter the regime from using chemical weapons again.”

President Trump on Thursday night described the strike as in the "vital national security interest" of the U.S., though a number of lawmakers urged caution on the administration taking military action in Syria without congressional authorization.

“The use of chemical weapons against innocent people will not be tolerated,” Davis said.

Thursday's strike was the first direct American assault on Assad’s government and the most significant military action of Trump’s young presidency.