'Before the strikes took place last night, North Atlantic Treaty Organisation allies exhausted all other possible ways to address this issue through the UN Security Council by diplomatic and political means, ' he said.
'Since this was blocked by Russian Federation there was no other alternative than to react the way they reacted at this time'.
During the NAC meeting, France, the United Kingdom and the United States briefed Allies on their joint military action in Syria overnight, as well as on the additional, non-military measures taken to reinforce the Chemical Weapons Convention. The alliance's chief said that the strikes "degraded the capabilities of Syria to conduct new attacks".
The U.S. -led strikes on Syria are justified because of the "murderous actions" of the Damascus government, an Israeli official told the Associated Press.
Pence is filling in for Trump at the Summit of the Americas in Lima.
"NATO considers the use of chemical weapons as a threat to worldwide peace and security, and believes that it is essential to protect the Chemical Weapons Convention", the statement added.
The Pentagon says a Russian "disinformation campaign" has already begun over the airstrikes.
US President Donald Trump on Friday launched precision air strikes on Syria in a combined operation with France and Britain.
Last week, a gas attack in Syria had killed at least 60 people and injured several others.
Russia's United States embassy warned the airstrikes will "not be left without consequences", while the Iranian Foreign Ministry threatened unspecified consequences.