Here is a basic outline of how America and its allies scoop up intelligence to guide the bombing raids, without a large ground force:
Satellites orbiting in space, high-altitude spy planes and a range of surveillance aircraft -- both manned and unmanned -- act as the "eyes" of the US military and its partners, tracking the movement of the IS group over hours and days.
The visual imagery is combined with eavesdropping and other information -- including spy networks on the ground -- to form a picture of the "battle space" for pilots and commanders.
Requiring less fuel and no pilot on board, the robotic drones can keep flying for hours, lingering over a potential target until an adversary appears.
The latest US fighter jets and bombers also are equipped with elaborate cameras and sensors on board, allowing them to scan the landscape for targets in a way that was not possible even several years ago.
The storied U-2 spy plane of Cold War fame remains one of the key aircraft for surveying the war zone, and is now equipped with state of the art sensors that provide detailed imagery.
The manned E-8 J-STARS aircraft, a modified Boeing 707 with a canoe-shaped radar under its forward belly, is highly valued by commanders, as it can track ground vehicles and relay other imagery in real time.
The unmanned Global Hawk, the robotic equivalent to the U-2 spy plane, performs a similar high-altitude surveillance role but can stay in the air for 28 hours, more than twice the endurance of the piloted U-2.
Other spy drones include the bat-winged, stealthy RQ-170 Sentinel, as well as turbo-prop Predators and Reapers, which can also be armed with Hellfire missiles.
The Pentagon says there have been more than 700 surveillance flights so far in an air campaign of more than 300 bombing raids.
While video and other imagery pours in, satellites and special aircraft act as the "ears" for intelligence gathering, picking up phone and radio communications -- known as "signals intelligence." A key tool for eavesdropping includes RC-135 aircraft, which can intercept phone calls from an altitude of 30,000 feet.
The US National Reconnaissance Office runs a constellation of secret spy satellites that can pick up electronic signals continuously over a wide area. And the US Army has "Trojan" trucks outfitted with antennae that can swiftly trace the location of a phone intercept.
Spotters and spies
Apart from sending in more spy planes and satellites, American intelligence agencies usually mobilize manpower and other resources to back up any major US military action, deploying CIA paramilitary operatives to work with local forces.
During the US-led invasion of Afghanistan in 2001, Central Intelligence Agency officers acted as forward air controllers for bomber planes, while US special operations forces advised Northern Alliance troops attacking the Taliban.
A similar model may be in effect in Iraq and Syria, with spotters for bombing strikes acting under the CIA's authority for covert operations. US officials will not confirm or deny if that is the case.
The CIA also will be working to gather intelligence the old-fashioned way, using contacts in the Kurdish forces, Iraqi government and some rebel elements in Syria.
Particularly in Syria, where Washington's spy network is considered weak, the Americans will look to Arab and other allies for insights into events there.