The Senate on Dec. 4 passed the fiscal 2013 defense authorization bill with vote of 98-0, including a last-minute amendment directing the Pentagon to provide Congress with a classified report on how it could enforce a no-fly zone over Syria.

Such a study could look at a number of options, including the use of Raytheon’s Patriot anti-missile batteries in Turkey and Jordan to keep Syrian aircraft from killing Syrian civilians, says Sen. Joseph Lieberman (I-Conn.).

Another option would be to fire precision-guided munitions from offshore to hit Syrian aircraft and prevent the Syrian government from firing against civilians, Lieberman said during a Senate floor speech.

The amendment, which passed by a vote of 92-6, should not be construed as a declaration of war or an authorization of the use of force in Syria, says amendment sponsor Sen. John McCain (Ariz.), the top Republican on the Senate Armed Services Committee. Rather, the classified assessment would help inform Congress about its options.

Sen. Rand Paul (R-Ky.) called the amendment “ill advised,” indicating that supporting Syrian rebels could be a mistake with unforeseen consequences.

Consideration of this year’s defense authorization bill was remarkable in that most amendments passed without the threat of a filibuster, a procedural move that winds up requiring a 60-vote margin for passage. In recent years, even routine legislation required 60 votes for passage.

The next step for the bill will be resolution by a House-Senate conference committee before both chambers vote on final passage.