The CIA and U.S. special operations forces have launched a secret campaign to hunt terrorism suspects in Syria as part of a targeted killing program that is run separately from the broader U.S. military offensive against the Islamic State, U.S. officials said.

The CIA and the U.S. Joint Special Operations Command are both flying armed drones over Syria in a collaboration responsible for several recent strikes against senior Islamic State operatives, the officials said. Among those killed was a British militant believed to be an architect of the terror group’s effort to use social media to incite attacks in the United States, the officials said.

The clandestine program represents a significant escalation of the CIA’s involvement in the war in Syria, enlisting the agency’s powerful Counterterrorism Center against a militant group that many officials believe has eclipsed al-Qaeda as a threat. […]