Sen. John McCain (R-Ariz) has returned to his self-proclaimed roots as a “Maverick McCain” by demanding U.S. military and Central Intelligence Agency action to tip the balance of the Syrian civil war in favor of rebel forces and against President Bashar al-Assad. Some other lawmakers on both sides of the aisle want a larger role in Syria too, but McCain has gone farther than most, saying he’ll block U.S. Army Gen. Martin Dempsey’s nomination for a second, two-year term as Joint Chiefs of Staff chairman until Dempsey divulges his personal opinion about the Syria conflict.

McCain and some lawmakers on both sides of the aisle, including Sen. Carl Levin (D-Mich), want the Obama administration to intervene militarily in Syria by imposing a no-fly zone and providing greater direct military assistance to anti-Assad forces. McCain’s high visibility on the issue is a reprise of his role in Libya in April 2011 when he made a surprise visit to support rebels who eventually ousted Libyan strongman Moammar Gadhafi.

McCain – a naval aviator who was a prisoner of war in North Vietnam – disagrees, however, with those who insist a no-fly zone isn’t practical because of Syria’s robust, integrated air defense system, which includes so-called “triple digit” surface-to-air missiles. McCain says U.S. forces have the means to overcome the Assad regime’s defensive systems.

McCain’s action on the Dempsey nomination is unusual but not unprecedented.

The issue is constitutional. Does the Senate’s duty to provide “advice and consent” on a nominee mean Dempsey must testify in public as to what advice he would give the president about Syria, even if the advice is given privately and ends up not being taken? McCain says the Army general’s views on Syria are relevant to his nomination. Dempsey argues he should limit his public testimony to policies that have been decided and announced.

Experts seem to agree that air-to-ground action – like that conducted two years ago in Libya – would be all but impossible in Syria because of the way government and rebel forces are intermingled on the ground. The vicious Syrian civil war, which has claimed 100,000 fatalities, according to the Associated Press, is made more complicated because some supporters of the rebels still hold government jobs in Damascus.

McCain – a naval aviator who was a prisoner of war in North Vietnam – disagrees, however, with those who insist a no-fly zone isn’t practical because of Syria’s robust, integrated air defense system, which includes so-called “triple digit” surface-to-air missiles. McCain says U.S. forces have the means to overcome the Assad regime’s defensive systems.

Others say it’s possible to enforce a no-fly zone, keeping the Syrian air force on the ground, without risking friendly aircrews. Norman Polmar, a defense analyst and author, told Defense Media Network a no-fly zone “would have saved hundreds if not thousands of lives” and “could have been established many months ago without risk to any American lives.”  Said Polmar: “We have the capability with AWACS [airborne warning and control] aircraft, ship-launched Tomahawk strike missiles, and a variety of unmanned aerial vehicles to control the airfields in Syria, preventing Assad from using his aircraft and even helicopters from attacking the civilian population.”

Few observers believe the “hold” on Dempsey’s nomination will be other than temporary. Still, McCain’s call for strong action in Syria is likely to define the debate over that country’s troubling civil war for some time to come.