WASHINGTON — A U.S. offensive in Syria against the radical Islamist group that beheaded an American journalist would likely be constrained by persistent intelligence gaps and an inability to rely on fleets of armed drones that have served as the Obama administration’s signature weapon against terrorist networks elsewhere, U.S. officials said.
The Pentagon has conducted daily surveillance flights along Iraq’s border with Syria in recent weeks as part of a push to bolster U.S. intelligence on the Islamic State without crossing into Syrian airspace and risking the loss of aircraft to that nation’s air defenses, officials said.
The CIA has also expanded its network of informants inside Syria, largely by recruiting and vetting rebel fighters who have been trained and equipped at clandestine agency bases in Jordan over the past two years, U.S. officials said.
Still, senior U.S. intelligence and military officials — speaking on the condition of anonymity to discuss sensitive operations — said American spy agencies have not yet assembled the capabilities that would be needed to target Islamic State leaders and provide intelligence with enough reliability to sustain a campaign of strikes.
“Our intelligence is improving since we began devoting the resources to doing that, but we still have only modest visibility into what is going on in Syria,” said Rep. Adam Schiff, D-Calif., a member of the House Intelligence Committee.
A senior U.S. intelligence official said “it would probably take some number of months to really build up the necessary intelligence architecture” to expand the U.S. air campaign underway in Iraq against Islamic State positions in Syria. “This is not going to end anytime soon.”
The Obama administration has counted on Predator and Reaper aircraft to carry out hundreds of strikes against al-Qaida targets in Pakistan and Yemen, countries where it has at least tacit permission to fly armed drones.
But the use of drones is far riskier in Syria, where the forces of President Bashar Assad guard the country’s airspace with missile batteries and fighter aircraft. The Islamic State seeks to overthrow Assad, and strikes against the group would be in his interest. But allowing American drones to reach cities such as Raqqah — an Islamic State stronghold — would also probably be seen by Assad as a threat, in part because such aircraft could gather valuable intelligence on his forces.
U.S. officials stressed that Mr. Obama has not made a decision to launch strikes in Syria — an action the administration has avoided since the start of that country’s civil war. But the video-recorded execution of American journalist James Foley this past week has prompted a re-evaluation of the threat posed by the Islamic State, an al-Qaida offshoot that holds other American hostages and controls territory across northern Iraq and Syria.
After gruesome footage of Mr. Foley’s killing appeared on the Internet, Mr. Obama warned that the United States would be “relentless” in its response. Gen. Martin Dempsey, the chairman of the Joint Chiefs of Staff, described the Islamic State as “an apocalyptic, end-of-days” organization that cannot be defeated unless it is “addressed on both sides of what is essentially at this point a nonexistent border.”
But while the border has been exploited by the Islamic State, it has been an impediment to U.S. spy agencies.
U.S. officials cited a failed attempt to rescue Mr. Foley and other U.S. hostages in July as indicative of the limits of U.S. intelligence. With information from sources including other hostages who had been released by the group, U.S. spy agencies believed they had identified with high confidence where Foley was being held. But by the time Army commandos arrived at the site, the hostages and their captors were gone.
U.S. officials said spy agencies have similarly singled out compounds where senior Islamic State operatives are believed to have been based. But it has been difficult to sustain surveillance of such targets long enough to be certain that those figures would still be in place if a strike were launched.