WASHINGTON (AP) — U.S. intelligence agencies are scrambling to salvage their surveillance of al-Qaida and other terrorists who are working frantically to change how they communicate after a National Security Agency contractor leaked details of two NSA spying programs. It’s an electronic game of cat-and-mouse that could have deadly consequences if a plot is missed or a terrorist operative manages to drop out of sight.

Two U.S. intelligence officials say members of virtually every terrorist group, including core al-Qaida, are attempting to change how they communicate, based on what they are reading in the media, to hide from U.S. surveillance — the first time intelligence officials have described which groups are reacting to the leaks. The officials spoke anonymously because they were not authorized to speak about the intelligence matters publicly.

The officials wouldn’t go into details on how they know this, whether it’s terrorists switching email accounts or cellphone providers or adopting new encryption techniques, but a lawmaker briefed on the matter said al-Qaida’s Yemeni offshoot, al-Qaida in the Arabian Peninsula, has been among the first to alter how it reaches out to its operatives.

The lawmaker spoke anonymously because he would not discuss the confidential briefing by name.

Shortly after Edward Snowden leaked documents about the secret NSA surveillance programs, chat rooms and websites used by like-minded extremists and would-be recruits advised users how to avoid NSA detection, from telling them not to use their real phone numbers to recommending specific online software programs to keep spies from tracking their computers’ physical locations.

House Intelligence Committee Chairman Mike Rogers, R-Mich., said there are “changes we can already see being made by the folks who wish to do us harm, and our allies harm.”

Sen. Angus King, I-Maine, said Tuesday that Snowden “has basically alerted people who are enemies of this country ... (like) al-Qaida, about what techniques we have been using to monitor their activities and foil plots, and compromised those efforts, and it’s very conceivable that people will die as a result.”

At the same time, NSA and other counterterrorist analysts have been focusing their attention on the terrorists, watching their electronic communications and logging all changes, including following which Internet sites the terrorist suspects visit, trying to determine what system they might choose to avoid future detection, according to a former senior intelligence official speaking anonymously as a condition of discussing the intelligence operations.

“It’s frustrating. You have to start all over again to track the target,” said M.E. “Spike” Bowman, a former intelligence officer and deputy general counsel of the FBI, now a fellow at the University of Virginia’s Center for National Security Law. But the NSA will catch up eventually, he predicted, because there are only so many ways a terrorist can communicate. “I have every confidence in their ability to regain access.”