NATO members are mulling plans for possible military action in Syria, but any intervention would only occur with a UN Security Council resolution and agreement from the alliance's 28 members, NATO supreme commander Admiral James Stavridis said Tuesday.

Stavridis told the US Senate Armed Services Committee that some NATO members considered targeting Syria's air defense network, a strategy successfully used in Libya in 2011.

But any NATO intervention would follow the same procedure which governed the action in Libya, Stavridis stressed -- a UN Security Council resolution and agreement from the alliance's membership.

"We are looking at a wide range of operations, and we are prepared, if called upon, to be engaged as we were in Libya," Stavridis said.

NATO's sole involvement in Syria's brutal civil war to date has been to position Patriot missile batteries along the Turkish border in order to prevent any air or missile launches from the Syrian side.

Stavridis said the Syrian conflict was deteriorating.

"The Syrian situation continues to become worse and worse and worse -- 70,000 killed, a million refugees pushed out of the country, probably 2.5 (million) internally displaced, no end in sight to a vicious civil war," he said.