"The authoritarian Assad regime did not get the message last year as it was hit by American missiles after it carried out chemical weapons attack against its own people", Mattis said adding that it carried used chemical weapons again this year.
Assad told his Iranian counterpart Hassan Rouhani that a USA -led attack on Saturday would increase Syria's resolve to "fight and crush terrorism in every inch" of the country.
Syria's foreign ministry on Saturday denounced Western strikes as a "brutal, barbaric aggression" hours after the US, France, and Britain launched a joint operation against military installations.
"We can not allow the use of chemical weapons to become normalised - within Syria, on the streets of the United Kingdom, or anywhere else in our world".
Public radio said that Israel had been informed ahead of time of the strikes that were carried out by the United States, France and Britain. These are not the actions of a man.
"I think we actually have to penalise Russian Federation and Iran for their support of Syria".More news: Pentagon briefing on U.S. airstrikes in Syria
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When asked about the possibility that airstrikes may have caused leakage of chemical agents, McKenzie said "we were able to minimize that", but said there were "probably some chemical agents" present.
President TrumpDonald John TrumpInfowars" Alex Jones blasts Trump over airstrikes: "He's crapping all over us' McCain to Trump: Airstrikes alone won't achieve objectives in Syria Top general: USA did not notify Russian Federation on Syria targets MORE announced the "precision strikes" against Syria in retaliation for an apparent chemical weapons strike last weekend in the Syrian town of Douma that left dozens of people dead.
Nasrallah echoed Syrian and Russian government denials that President Bashar al-Assad's forces were behind the attack. This complicated situation will be against US interests. For them, Syria is less important than US President Donald Trump's decision on the Iranian nuclear deal, due in less than a month, on May 12.
Photo released by Iranian media reportedly show the T-4 air base in central Syria after a missile barrage Monday.
He reaffirmed Russia's view that a purported chemical attack in the Syrian town of Douma that prompted the strike was a fake.
Ali Shirazi, liaison for Iran's Supreme Leader Ayatollah Ali Khamenei to the elite Quds Force, threatened that Tehran will destroy Israel if it doesn't stop its "childish game". An Israeli F-16 was shot down by the Syrian Army, although the pilots survived.