Defense Secretary James Mattis said the US used "a little over double" that of a 2017 missile strike on a Syrian air base, which involved 59 Tomahawk missiles.
The US fired more than 118 missiles on Syria on Friday in precision strikes that were fired in response to a suspected chemical weapons attack last weekend.
US Defense Secretary James Mattis confirmed that the US used more than twice as many missiles as it did in a 2017 strike on Syria's Sharyat Airbase on April 7, 2017. That attack used 59 Tomahawk missiles, and was ordered by President Donald Trump, who said the action was in response to a chemical attack three days earlier.
"We used a little over double the number of weapons this year than we used last year," Mattis said on Friday.
"We were very precise and proportionate, but at the same time it was a heavy strike," he said.
It's unclear yet what weapons were used. But if the Raytheon-produced Tomahawk missiles, which have an estimated cost of $1.4 million each, were used in Friday's strike, that puts the minimum weapons cost at $165.2 million.
Friday's strike was launched in retaliation for a suspected chemical weapons attack last Saturday which killed dozens of people, and injured scores more.
Shortly after the attack, President Donald Trump and French President Emmanuel Macron agreed to a "strong, joint response" if it was found the attack believed to be made by Assad's regime used a chemical weapon. UK Prime Minister Theresa May reportedly also spoke with Trump this week.
France and the UK have joined the US military operation.