The United States military is flying both manned and unmanned surveillance aircraft over northeastern Nigeria in the search for more than 250 schoolgirls kidnapped by Boko Haram, Pentagon officials said today.

The move reflects a growing U.S. participation in the search efforts for the girls, though Pentagon officials still say the U.S. is not planning a broader operation to find the girls.

An MC-12 Liberty reconnaissance aircraft began flying missions on Monday, and an unmanned long-range Global Hawk surveillance aircraft flew a mission over northern Nigeria today, officials said.

The MC-12 is a Beechcraft propeller aircraft that carries a crew of four and is equipped with reconnaissance and surveillance equipment. Two analysts sit in the aircraft's fuselage monitoring real-time information being relayed from visual and communications sensors located underneath the plane's fuselage.

The MC-12 is being flown by a military crew and had been flying missions over Mali from neighboring Niger, one official said. The United States also has unarmed Predator drones that fly out of Niger's capital, Niamey, conducting reconnaissance missions over Mali to assist French forces that have been fighting Islamic extremists in the northern part of that country.

While speculation has centered on those drones being redirected to the search over Nigeria, it appears the unmanned RQ-4 Global Hawk will assume that mission. U.S. officials confirmed that a Global Hawk aircraft flew over northern Nigeria today and plans call for additional flights in the region. The jet-powered aircraft can remain over an area for as long as 24 hours and is equipped with long-range optical and surveillance equipment, officials said.

The aircraft is likely flying its missions from U.S. bases in Europe. The U.S. Air Force has Global Hawks stationed at the Naval base in Sigonella, Italy.

Last week, Nigeria accepted the American offer to send an interagency coordination cell to Nigeria to assist with the search for the missing girls. The team of 27 Americans now in Nigeria includes a military component of 16 who are providing assistance for the search, officials said. Pentagon spokesmen have said consistently that there are no plans for the United States military to conduct an operation to search for the girls.

However, they have said that there have been ongoing discussions with Nigeria about what intelligence the United States could share with Nigeria as part of the search efforts. There are existing limitations on how much intelligence gleaned from the flights can be provided to the Nigerians.

Gen. David Rodriguez, U.S. Africa Command's senior commander, visited Nigeria on Monday and today as part of a pre-scheduled trip that included discussions with senior Nigerian civilian and military officials.

Planned in March so that Rodriguez could meet Nigeria's defense leaders, his discussions this week touched on the ongoing efforts to find the missing schoolgirls who were kidnapped on April 15.