WHITE HOUSE — U.S. President Barack Obama continues to face pressure to work with other nations to establish a no-fly zone in Syria to protect civilians and relieve pressure on Syrian rebels. A no-fly zone remains among the options, but experts say it would require careful calculations and difficult decisions.
Critics continue to accuse the president of sitting on the sidelines as the death toll in Syria - now estimated at more than 20,000 - mounts and fighting intensifies between the government of President Bashar al-Assad and rebels.
In the case of Libya in 2011, the United States led a NATO air campaign with the support of key European and Arab allies, and United Nations Security Council backing. U.S. military planners calculated a good chance of success on the ground.
Cautious approach in Syria
Obama and other officials have maintained that the Syria situation is much more complicated. They point to financial and other U.S. sanctions announced in recent months, and complex consultations with international partners.
Obama addressed the more cautious approach regarding Syria in remarks earlier this year with visiting British Prime Minister David Cameron after a reporter asked about a potential no-fly zone in Syria.
"One of the things I think that both of us have learned in every one of these crises, including in Libya, is that it is very important for us to make sure that we have thought through all of our actions before we take those steps," said the president.
Advocates push for no-fly zone
Robert Zarate, policy director of the Foreign Policy Initiative, a conservative Washington research group, was among 62 analysts who urged Obama to work to create a no-fly zone.
Zarate calls it "regrettable" that the U.S. has not taken stronger action to avoid the kind of bloodshed in Syria that it acted to prevent in Libya.
"A safe zone can help to protect civilians who are being indiscriminately targeted by the Assad regime. Moreover it can also help the U.S. and its partners in the region to sort of create space in which they can carefully vet members of the armed opposition in particular and figure out how we can work with them more effectively," he said.
The U.S. has been consulting closely with Turkey and other nations in the region on next steps.
Myriad plans under consideration
Obama's counterterrorism adviser, John Brennan, recently said the president is carefully considering implications of any major decision.
"The president has kept us all quite busy making sure that we're able to do everything possible that's going to advance the interests of peace in Syria and not, again, do anything that's going to contribute to more violence," said Brennan.
For now, Secretary of Defense Leon Panetta says the U.S. remains focused on non-lethal assistance to Syria's rebels, humanitarian aid, and preventing any use or diversion of Syria's chemical weapons. A no-fly zone, he said, "is not a front-burner issue."
Joint Chiefs of Staff Chairman Martin Dempsey ruled out any unilateral action, but went a bit further, mentioning consultations with Turkey and Jordan.
"They're both interested mostly in the effects that could spill from Syria into their countries. Both have examined the - the possibility of a safe haven. And with a safe haven would probably come some form of no-fly zone," said Dempsey.
Considering specifics of no-fly zone
Chris Chivvis, an analyst with the RAND Corporation, said strategic and humanitarian rationales for stronger action in Syria have been met.
He cautioned that any intervention must have a high probability of success and would require not only air power to suppress Syrian government defenses, but eventually ground forces as part of "post-conflict stabilization."
"If you are going to impose a no-fly zone you probably should be ready to insert ground forces. They don't have to be U.S. forces, but you need to have some country that is ready to insert a post-conflict stabilization force," said Chivvis.
Chivvis said a Syria no-fly zone would have to be "significantly larger numerically and more sophisticated" than was the case in Libya. The zone could probably be established in as little as one week, he said, but how long it would have to be maintained remains a question.