If the Obama administration actually takes the fight to the Islamic State in Syria, it would likely do so in stages, hitting the easiest targets first and the most difficult ones later as it develops a richer picture of the battlefield, former intelligence officials and experts say.
"That's generally how an air war progresses," retired Air Force two-star Maj. Gen. Jim Poss, a career intelligence officer, told Foreign Policy.
Just last year, the Pentagon contemplated bombing Syria after President Bashar al-Assad unleashed chemical weapons -- sarin gas that did not discriminate between fighters and citizens. The Pentagon envisioned a brief, decisive campaign against stationary targets. The mission now under consideration is far more challenging: Hit smaller, mobile targets difficult to identify without ground forces, all the while facing a forewarned enemy that prepared while President Barack Obama weighed acting.
Depending on when the "go" order is issued, U.S. military personnel could quickly identify the "low-hanging fruit" targets -- armored vehicles, artillery, and other hardware relatively easy to spot from the air. The United States could establish a "no-drive" zone to prevent enemy forces from crossing the border into Iraq and armed aircraft could strike them once they were identified, Poss said.
The next stage would require refined intelligence gathered from drone feeds taken over days or weeks and would hit ammunition supply points and other such targets. The most difficult mission -- one that the White House may not have an appetite for -- would go after the Islamic State's leadership.
Launching that phase could take weeks or even months, as drone operators and intelligence analysts amassed a deeper understanding of militant leaders' "patterns of life."
"It takes hours and hours of video in order to put it together," Poss said, noting that it's doable. "It's almost shocking how well we get to know the habits of our targets."
The Atlantic Council's Faysal Itani told FP that the Islamic State has "some highly visible assets," including military headquarters, energy assets, and lines of communications through open areas.
"They are not some murky, underground insurgent group. In many ways, their ambition has made them more visible."
But their fighting force is highly mobile, making it difficult to target, and Raqqa, the group's base in northern Syria, is also more complicated as it is a dense, urban environment, he said.
The scope, objective, and length of a Syrian mission -- or even whether one will materialize -- remain very murky. Some administration officials, including Defense Secretary Chuck Hagel, have warned against ignoring the Islamic State. Others, including Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey, have been more circumspect. Earlier this week Dempsey hinted that the Sunni militants are a direct threat to the American homeland. Then on Aug. 25, Dempsey's spokesman clarified that the group formerly known as ISIS "will soon become" a threat to the United States and Europe.
The Islamic State "should be pressured both in Iraq and in Syria," Dempsey's statement read. The chairman was "preparing options" to attack militants in both countries with "a variety of military tools, including airstrikes."
But first unmanned drones must survey Syria from above. The United States has yet to acknowledge publicly that those flights will even take place, though there are a variety of reports that indicate they have already begun. A Pentagon spokesman on Wednesday said the Defense Department would not announce publicly if and when such flights were to begin.
Once such intelligence, surveillance, and reconnaissance, or ISR, operations produce useable intelligence, the Obama administration will have a much clearer picture of the Syrian situation and terrain, where the Islamic State has its origins.
Beyond tactical obstacles, Obama must decide if the United States will get into bed with Assad for the purposes of fighting the Sunni militants who have been waging war against him since 2011. U.S. officials dismissed out of hand reports that Washington has shared intelligence with Damascus -- an incredible proposition for an administration that has been trying to eliminate Assad.
"We are not coordinating with the Assad regime on the operations that we're conducting in Iraq or the operations or any efforts to combat ISIL," Pentagon spokesman Rear Adm. John Kirby said on Tuesday.
The United States needs informants in Syria and aircraft in place to precisely target Islamic State fighters. The U.S. military has a formidable arsenal of armed drones and piloted aircraft but its local spy network appears to be lacking. American efforts to "vet" rebel forces in Syria have been limited. And the U.S. military doesn't have a deep and reliable network of friendly forces on which it can rely.
In July, U.S. commandos failed to rescue American journalist James Foley and others held in Syria after receiving what one U.S. official called "bad intelligence" about their location, which had come from local spies and previously freed hostages. When the American forces arrived, no hostages were found.
Intelligence officials also acknowledge they don't know exactly where Abu Bakr al-Baghdadi, the Islamic State's leader, is. However, the United States' ground intelligence capabilities are increasing. Current and former U.S. officials say that the intelligence community, and in particular the CIA, has at least the beginnings of an informant network there. They credit the spy agency's training of Syrian rebel fighters at a base in Jordan. Additionally, the U.S. military may have to insert a small number of special operations forces into Syria, potentially embedding with those moderate forces, to assist with an air campaign.
Syria is not completely a black box to U.S. spies, though. In August 2013, American intelligence picked up indications three days beforehand that the Syrian regime was poised to launch the lethal chemical attack that killed more than 1,400 people and set the stage for a possible U.S. military strike on Syria, according to an assessment the White House released when Obama was building a public case for military action last year -- a step he ultimately didn't take.
But chemical weapons production and storage facilities make much better targets. Now the United States would have to contend with much more nimble targets.
It would also potentially face a Syrian air defense system that the Pentagon considers sophisticated enough to pose a threat to invading aircraft, as it is unclear whether Assad would confront American aircraft targeting his Islamic State enemies. The risk to U.S. aircraft and personnel has raised the question of whether the military would seek the Syrian government's permission to strike the Islamic State and its assurance that Syrian forces won't fire on American planes.
Walid Muallem, Syria's foreign minister, has hinted that the Assad regime is open to working with the Americans on airstrikes.
"Syria is ready to cooperate and coordinate on the regional and international level in the war on terror," Muallem said at a news conference on Monday. He also suggested that the Americans should have worked with the Syrians in July on the attempt to rescue Foley. "Had there been prior coordination that operation wouldn't have failed," Muallem said. But he made clear that the Syrian government would not merely accede to another U.S. military operation on its soil; any U.S. airstrikes conducted without Syrian permission "will be considered as aggression," Muallem said.
Direct consent from the government might not be required, however. For years, the United States has launched drone strikes against terrorists and Taliban militants in Pakistan with an implied or tacit permission from the government, as opposed to an outright invitation.
Although it's likely the United States would need to deploy special operations forces inside Syria, there is precedent for conducting an air-only campaign. A U.S.-led coalition didn't have forces inside Libya during the 2011 bombing campaign.
Ralph Jodice, a retired Army three-star general who served as the NATO Combined Forces Air Component commander during Operation Unified Protector in Libya, said that operation relied heavily on intelligence, surveillance, and reconnaissance.
"You take all of those things and fuse them together to build a picture," Jodice said. "That can happen quickly or it can take weeks."