Latest developments

— Four Shiite Lebanese men were killed Sunday in an ambush in a volatile area by the border with Syria, hiking already high sectarian tensions and concerns over the spillover of the civil war raging next door. Gunmen from the families of the slain Shiites took to the streets and set up roadblocks between their town and the neighboring Sunni majority town of Arsal, accusing residents there of being behind the killings.

— Late Sunday, an explosion shook the western Damascus neighborhood of Mazzeh, and Syrian state TV said “terrorists” — the term the regime uses for rebels — had attempted to hit a military airbase there. The Britain-based Syrian Observatory for Human Rights, which has a wide network of activists on the ground in Syria, said a car bomb detonated at a checkpoint near the military airport in Mazzeh. It said there were reports of casualties, but it did not have specific numbers.

— In a recent attack that underlined heightened sectarian hatreds, activists said videos that surfaced last week show extremists fighters of an al-Qaida affiliated group blowing up a Shiite shrine in a village in the eastern Deir al-Zour province in Syria, along the border with Iraq.

Associated Press

The Obama administration, trying to avoid getting drawn deeper into Syria’s civil war, has pointed to the U.S.-led invasion of Iraq in 2003 as a symbol of what can go wrong when America’s military wades into Middle East conflicts.

But experts say the White House is looking at the wrong Iraq war, especially as the U.S. reluctantly considers a no-fly zone over Syria to stop President Bashar Assad from continuing to use his air power to crush rebel forces or kill civilians.

A no-fly zone is a territory over which warring aircraft are not allowed to fly. The U.S. and international allies have enforced them in several military conflicts over the past two decades.

When he took office in 2009, President Barack Obama promised to end the U.S. war in Iraq as an example of refocusing on issues that had direct impact on Americans. By the time the U.S military withdrew from Iraq in 2011, almost 4,500 American soldiers and more than 100,000 Iraqis had died. The war toppled Saddam Hussein but also sparked widespread sectarian fighting and tensions that still simmer.

But when considering a no-fly zone, experts point to 1992, a year after the Gulf War. That’s when the U.S. imposed a weakly enforced no-fly zone over southern Iraq and could not prevent Saddam, a Sunni Muslim, from persecuting and killing hundreds of thousands of Shiites whom he viewed as a political threat.

That failure is now being used as a case in point of why the U.S. should or shouldn’t police the Syrian sky to prevent Assad from accelerating a two-year death toll that last week reached 93,000.

The White House is undecided on whether it will impose a no-fly zone over Syria, as some have demanded. Egypt’s president, Mohammed Morsi, on Saturday called for a U.N. endorsed no-fly zone.

“We’ve rushed to war in this region in the past. We’re not going to do it here,” Obama’s chief of staff, Denis McDonough, said Sunday on CBS television’s “Face the Nation.”

Vali Nasr, a Middle East expert and dean of the John Hopkins’ School of Advanced International Studies, argued for a no-fly zone “to prevent Assad from completely dominating this war for all practical purposes. And we need to create a no-fly zone to create a safe zone for refugees that Assad can’t reach.”

Nasr, who held a senior State Department job during the first two years of the Obama administration, said Friday that there are risks, “but perhaps the risks are exaggerated. And what it showed in Iraq is that it does not have to be a slippery slope into a larger war.”

On the flip side, said retired Navy Adm. William Fallon, “there’s no way to do this in a standoff — ‘We’re just here to help, not going to get our hands dirty.’”

Last Thursday, the White House deputy national security adviser Ben Rhodes announced the Obama administration has agreed, after months of hesitation, to start supplying the rebels with upgraded military aid. That decision came as a result of stronger intelligence indicating that Assad has used chemicals weapons against his people multiple times this year.

Rhodes would not detail the type of aid. But military officials and experts said it probably would include small-arms weapons, shoulder-fired anti-tank grenades and ammunition.

That would mark the White House’s first lethal shipment to Syria. Until now, the administration has mostly supplied the rebels with military equipment, such as body armor and communications devices, and humanitarian aid to the Syrian people.

Obama has not ruled out imposing a no-fly zone in Syria, Rhodes said.

Republican Sens. John McCain of Arizona and Lindsey Graham of South Carolina, have been pushing for a no-fly zone in Syria, and last week said supplying arms and ammunition to rebels is not enough to curb Assad’s air power. They raised the option of using cruise missiles, which can be launched from outside of Syria, as one way of securing Syria’s air space.

On Sunday, Sen. Saxby Chambliss of Georgia, the top Republican on the Senate Intelligence Committee, agreed. “A no-fly zone may be the, ultimately, tactic that has to be taken,” he told NBC’s “Meet the Press.”