More broadly, the Obama administration is also pressing for Iraqi Prime Minister Nouri al-Maliki to take steps to make his Shiite-dominated government more inclusive. Obama said last week that any short-term U.S. military actions in Iraq would not be successful unless they were accompanied by political changes by the government in Baghdad.
It's unclear whether the CIA and the NSA have been able to locate the top insurgent figures, such as Abu Bakr al-Baghdadi, the ISIL's leader. Baghdadi, who was released in 2009 after spending four years in U.S. military custody in southern Iraq, came away with an appreciation of American monitoring technology that made him an elusive target once he took command, said Richard Zahner, a retired Army general and former senior NSA official.
But intelligence agencies have been tracking the ISIL for years, officials say, watching closely as it grew stronger in the Syrian civil war and began to challenge the Shiite-dominated Baghdad government.
"We have had a real interest, along with our friends the Jordanians, the Turks and others, in doing all we could to watch these guys," said Rep. Jim Himes, a Connecticut Democrat on the House Intelligence Committee. "We have a reasonable sense for the nature of ISIL, but we have very limited visibility into who is doing what to whom right now."
The CIA and other agencies are assembling detailed dossiers known as "targeting packages" that amount to profiles of insurgent commanders, including as much day-to-day information as can be gathered about their location, movements, associates and communications. Those packages can be used to target the subjects for drone strikes or other military action, though they also can be used for nonlethal purposes, current and former officials say.
More than a year ago, the CIA's Counterterrorism Center expanded a team of officers at the agency's headquarters in northern Virginia to track and target al-Qaida-linked militants operating in Syria and Iraq. Those efforts are now intensifying, U.S. officials say. They would not discuss in detail their efforts to monitor the Iraqi insurgents for fear of tipping them off. Already, they said, key leaders communicate through couriers and take other steps to avoid eavesdropping.