As Libyan ruler Muammar Qaddafi continues his violent attacks on rebels in strategic cities and the country hurtles toward civil war, western countries are indicating that the economic sanctions, asset freezes, travel restrictions, and arms embargoes they've already discussed may give way to humanitarian or military intervention, in an effort to force Qaddafi from power.

The U.S.--which has removed an obstacle to more aggressive action by evacuating most of its citizens from Libya--has begun moving warships and aircraft toward the country and dispatched aid workers to Libya's borders with Tunisia and Egypt to help refugees. On Monday, Secretary of State Hillary Clinton said the administration was consulting with allies about instituting a no-fly zone over Libya to prevent the Libyan Air Force from attacking civilians--a tactic used in Iraq and Bosnia in the 1990s.

In Europe, a French official said humanitarian aid--and not military action--was the priority, while British Prime Minister David Cameron said he would not rule out "the use of military assets." Russia's foreign minister, meanwhile, dismissed the no-fly zone proposal as "superfluous" and instead endorsed the sanctions passed by the U.N Security Council over the weekend. Any Security Council approval of a no-fly zone would require Russia's consent.

So what are the chances of some sort of more serious action being taken?

Mark Landler and Thom Shanker at The New York Times say a no-fly zone would probably only be imposed in conjunction with the U.N. or NATO and that direct military action is unlikely, especially since it "could undermine the legitimacy of the Libyan revolt as an internal, grass-roots movement" and be construed as an oil grab. The U.S. may have announced its military maneuvers and calculations more to pressure Qaddafi, encourage the military to turn on him, and show support for the protesters, Landler and Shanker note. In addition to the no-fly zone, they claim the U.S. is considering "using military transports to deliver food and medicine, or evacuating Libyans who want to leave the country," but not mobilizing ground troops.

Time's Massimo Calabresi explains that Qaddafi's categorical refusal to relinquish power and the specter of a humanitarian catastrophe could indeed force the international community to intervene militarily in a U.N.-led mission, but also notes concern that "the absence of a clear sense of what might come after a [Qaddafi] ouster raises fears of a repeat of the Black Hawk Down scenario [in Somalia in the 1990s], in which military forces supporting a humanitarian mission got caught up in a vicious local power struggle."

There are additional concerns about military intervention. Edward Rees at The Atlantic states that a no-fly zone might prove ineffective in Libya because the country is large and offers no good air bases to use. The countries enforcing the no-fly zone also risk shooting down the wrong planes, mistakenly bombing protesters, and getting sucked into a bombing campaign or conflict on the ground.

Beyond these logistical concerns, says Gideon Rachman at the Financial Times, there is the problem of the two "never agains." On the one hand, the U.S. and its European allies want to prevent the kinds of atrocities and war crimes that occurred in Rwanda and Bosnia from happening again. On the other hand, they have no appetite for an "armed western intervention to overthrow an Arab dictator that came out of the Iraq war," and "the Iraq experience is proving more powerful." Given that "there is still a strong chance that the Libyans themselves will get rid of their own dictator," Rachman concludes, "outside military intervention now could be a mistake."