A U.S. Navy pilot returns safely to the flight deck of the aircraft carrier USS Enterprise.
Imposing a no-fly zone over Libya is among the most talked-about options on the table as Western leaders struggle to find ways to do "something" while avoiding being dragged into a bloody civil war.
No-fly zones are easy to propose, hard to impose and have, at best, a mixed history of success.
While some push for the West to do more than watch, others warn that a no-fly zone won't make a meaningful military difference and could be the slippery slope leading to another U.S.-led war in a Muslim country. One thing is certain, without American warplanes, carriers and command-and-control, there will be no NATO-imposed no-fly zone.
What is a no-fly zone?
It's an imposed area where flying is banned - backed up by circling warplanes ready and mandated to shoot down any "outlawed" aircraft. It's designed to prevent a pariah regime from using combat aircraft against its own people. Simple in concept, no-fly zones are tough to impose and require a major military commitment - several hundred aircraft - to make them effective around the clock for months or longer. They may look tough but don't always tip the military outcome.
How is one created?
Once the zone is designated, either by UN Security Council resolution, which makes it legal under international law, or because the great powers impose it, it must be enforced.
Pairs of warplanes patrol the zone (a Libyan no-fly zone would probably require several pairs all the time to effectively cover the long coastal area where almost all of the population is located) backed up by airborne refuelling tankers orbiting offshore and multiple command-and-control aircraft called AWACS with sensitive radar that control the battle space.
Scores of warplanes, more than a dozen tankers and many additional aircraft - for instance a rapid-reaction team with helicopters and ground-attack aircraft to find and rescue any downed pilots - would be needed. To enforce a no-fly zone over tens of thousands of square kilometres 24/7 would be beyond the capacity of any single nation save the United States, although some European allies, notably Britain, France, Germany and Italy could, if they wanted, make significant contributions.
A no-fly zone over Libya would require several squadrons of land-based warplanes flying from air bases in Italy and maybe the British base on Cyprus, plus at least one of the massive U.S. aircraft carriers, backed up by a smaller British or French carrier.
Are they legal?
A no-fly zone, like any sort of blockade by a belligerent, is an "act of war." It is legal only if explicitly authorized by the UN Security Council. (China and Russia have already said they are opposed.)
NATO warplanes acting under a UN mandate shot down four Serb fighter-bombers in 1994, the alliance's first-ever combat in the no-fly zone over Bosnia. In 1999, after failing to get UN Security Council approval, NATO unilaterally (and many claim illegally) imposed a no-fly zone and then launched an air war against Serb forces in Kosovo. Canadian F-18s led scores of bombing runs.
The United States, along with Britain and France, imposed no-fly zones over northern and southern Iraq in 1991. Hundreds of Iraqi missile launchers and radar sites were attacked over the next 12 years until the 2003 Iraq war began.
Would NATO warplanes need to knock out Libya's anti-aircraft defences first?
"A no-fly zone begins with an attack on Libya to destroy the air defences," says U.S. Defence Secretary Robert Gates. Others believe that a full set of pre-emptive strikes against Libya's array of ill-maintained, outdated Soviet surface-to-air missiles wouldn't be needed and U.S. warplanes could wait until threatened or "locked on" by targeting radar.
That's easy for armchair strategists but tough on pilots strapped into cockpits knowing that radar-guided or heat-seeking missiles are only seconds away from a "kill" if launched. Politicians would have a hard time explaining to bereaved widows if they opted to leave Libya's air defences untouched while sending pilots to patrol hostile skies. Nevertheless, no allied warplanes were lost (a pair of helicopters collided) during the 12-year Iraqi no-fly zone and the risks over Libya are probably as low or lower.
What are the biggest risks?
Probably ineffectiveness, followed by mission creep and the danger of being dragged into another war. Spending tens of millions and flying thousands of sorties a month to deny Moammar Gadhafi a handful of ineffective bombing runs with aging MiG fighters, mostly used to try and knock out ammunition dumps, may initially look impressive but may also fail to tip the balance. Most of the killing is being done by artillery, mortars and machine guns, all weapons that are terrifyingly effective against civilians and ill-trained rebels.
The prospect of Western warplanes circling impotently overhead while massacres continue could be the slippery slope that results in a call for ground attacks. And if those fail, perhaps ground troops to protect "safe havens" - such as the ones that didn't work in former Yugoslavia despite NATO's no-fly zone. In Bosnia, Kosovo and Iraq, no-fly zones were always followed, albeit for different reasons, with major ground force deployments.
Libya has one additional complication. Dozens of humanitarian flights are shuttling in and out of the rebel-held zone and airports close to Libya's borders as aid is flown in and refugees evacuated. The danger of shooting down one of those flights would haunt any no-fly zone combat patrol.