The United States has deployed drones to Nigeria to help search for more than 200 schoolgirls kidnapped by militant group Boko Haram, officials confirmed Wednesday.

White House Press Secretary Jay Carney said “unmanned, unarmed” aircraft had joined reconnaissance flights over a swath of Nigeria where Boko Haram is believed to be holding the girls hostage. Carney cautioned during a news conference that the area of greatest suspicion still covering an expanse of land “along the size of West Virginia.”

The announcement comes as some U.S. lawmakers are urging the use of force to rescue the Nigerian girls. Senators in both parties recently floated the idea of using special forces to aid in the search, and Arizona Republican Sen. John McCain went further on Tuesday. “I certainly would send in U.S. troops to rescue them,” McCain told to the Daily Beast.

Carney, however, said U.S. counterterrorism experts dispatched to Nigeria would limit their activity to an “advisory capacity,” focused on finding the girls.

Recent international attention and internal protests have ratcheted up pressure on Nigeria’s government to rescue the girls and crack down on Boko Haram. Over the last five years, the extremist group has waged a campaign of bombings, massacres and kidnappings in northern Nigeria that has claimed an estimated 1,000 lives.

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