Although pressure is rising in France and other European nations for military intervention to stop the bloodshed in Syria, leaders are stymied by an unpleasant reality: Lessons learned from last year’s NATO operation in Libya suggest that taking down President Bashar al-Assad would be impossible without large-scale involvement by the United States.

The urge to do something is particularly strong in France, which has historical ties to Syria and whose then-President Nicolas Sarkozy rallied the United States and other allies around his proposal to bomb government forces in Libya. Moreover, France is the country where the idea of a “right to intervene” to save lives abroad was born, and where it has since expanded in the eyes of many into a “duty to intervene.”

Frustrated by Russian and Chinese vetoes in the U.N. Security Council and President Obama’s reluctance to commit U.S. forces, some French opinion leaders have criticized President Francois Hollande for failing to organize an international intervention even without a Security Council mandate. The implication of their challenge is that a resolute France could persuade Obama to change his mind or that a French-led European coalition could act with neighboring Turkey.

Sarkozy’s one public gesture since his defeat at the polls in May, for instance, was to accuse Hollande of vacationing at the beach while Syrian rebels die at the hands of Assad’s army. Sarkozy’s followers swiftly joined in, eager to portray Hollande as inexperienced in foreign affairs and unable to show leadership.

Bernard Henri-Levy, the philosopher and commentator who promoted Libya’s opposition leaders with Sarkozy and the public last year, said recently he also is disappointed with Hollande for his failure to intervene militarily and suggested that he and other European leaders are overestimating the obstacles to overthrowing Assad.

“Everybody knows that not a lot is necessary anymore to finish off the government,” Henri-Levy said in a newspaper interview, suggesting that the Turkish air force might be sufficient. “We just need a pilot in the plane.”

Eager to demonstrate initiative in the face of such criticism, Hollande announced recently that if Syria’s disparate rebel groups would come together around a government in exile, France would recognize it immediately. Similar support from Sarkozy last year helped the Libyan rebel movement come together against Moammar Gaddafi. But France and a half-dozen other nations have been trying without success to prod Syrian rebel groups into a unified command for months.

The French Foreign Ministry revealed last week that France is providing humanitarian aid directly to rebel-controlled towns inside Syria. According to reports in Paris, France also has provided training and non-lethal military equipment such as night-vision goggles.

Although dismissed by specialists, Henri-Levy’s exhortations fell into a generally receptive audience because the Libyan intervention is viewed here as a proud success for France and its military. Not only did Sarkozy rally others in Paris to start the operation but not a single French pilot was lost, even though French aircraft flew about 25 percent of the strike missions during seven months of bombing against 7,600 targets.

NATO’s “lessons learned” studies after the Libya intervention paint a different picture. They show that last year’s casualty-free war was possible largely because the United States destroyed Libya’s air defense system and disrupted its command-and-control network with an opening salvo of sea- and air-launched cruise missiles and guided bombs that no European country, or combination of countries, could have mustered.

“The French and British simply would not have had the means to do that,” said a senior NATO officer who helped direct the Libya war. “The U.S. is really the only one with that kind of counter-air-
defense capability.”

Despite the public pressure, French military specialists recognize how the Libya war was conducted and what it says about the possibility of a similar intervention in Syria.

Suggestions from the refugee-burdened Turkish government and others in Europe that a humanitarian no-fly zone could be set up near the Turkish border do not make military sense, military specialists said. This is because Syria’s Russian-supplied integrated air defense network would have to be taken out — from the border south to Damascus and beyond — to make defending such a zone with allied air patrols possible, he said.

Syria’s shooting down of a Turkish F4 Phantom on a border-skirting reconnaissance patrol in June showed that Assad’s air defenses are already on alert, the NATO officer pointed out, speaking on the condition of anonymity to enable a frank discussion.

If the mission were limited to protecting a narrow humanitarian corridor along the border — and not removing Assad — this could be done by positioning antiaircraft missiles on the Turkish side of the line and warning Syrian planes against violating a no-fly zone, said Francois Heisbourg, a military expert at the Foundation for Strategic Research in Paris. But it would be unwise to try anything like that without a U.N. mandate, he added, because it would be an act of war with hard-to-control consequences and would set a dangerous precedent.

The pressure for action has been particularly oriented toward humanitarian concerns such as a border safe zone because the “right to intervene” remains vivid in the French public’s mind. The concept was pushed onto the international scene in the 1980s by Bernard Kouchner, who had helped start Doctors Without Borders a decade earlier and, as “the French doctor,” stirred worldwide concern over Vietnamese boat people after the fall of Saigon. He was foreign minister in the early Sarkozy years.

In any case, after-action studies show that, even after NATO assumed command of the Libya bombing, the United States remained the only country with sufficient intelligence-gathering drones to permit NATO officers at their Naples headquarters to get a picture of the battlefield, and the only country with enough aerial refueling tankers to keep NATO aircraft in the air. The United States flew about 80 percent of aerial refueling flights over seven months of bombing, the studies found.

The U.S. Predator drones were particularly important in the Libya operation because NATO target planners were ordered to avoid civilian casualties. Although several mistaken attacks occurred, killing civilians, the officer said, two-thirds of the objectives singled out for bombing by targeting specialists were turned down because of a danger that civilians might be hurt.

A Syria intervention would be staggeringly more difficult because the country is not clearly divided into areas controlled by the army and others controlled by the rebels.

Moreover, Syrian rebels fighting inside the country are divided into multiple groups, some geographical and others with an Islamist agenda hostile to the West.making it difficult to coordinate to avoid friendly-fire incidents.

The Syrian military also is substantially more formidable than Libya’s, the officer said, with a trained officer corps that Gaddafi lacked and more than 300,000 regulars, 5,000 tanks and 500 warplanes.Finally, he said, in the Libya operation NATO forces benefited from the most powerful weapon of all: “There was a lot of luck involved.”