U.S. support to Nigeria beset by complications

The United States is now using drones and manned surveillance aircraft over Nigeria in the search for the hundreds of schoolgirls kidnapped by Boko Haram.

But signs of them are yet to emerge, as the task is complicated by the possibility that the girls have been separated into groups.

The U.S., which is supporting the Nigerian government's efforts, will continue to deepen its efforts, Defense Secretary Chuck Hagel said Wednesday while traveling to Saudi Arabia.

However, "I have seen no intelligence come back that I am aware of that shows that we've located those girls," he said.

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The assets provide some of the best tools to try to find the girls, but the Nigerian government has shown some reluctance to use U.S. help.

As it is, the U.S. is not sharing raw intelligence from its surveillance aircraft with Nigeria's armed forces.

This is because the countries have still not established the intelligence-sharing protocols and safeguards needed for an intelligence-sharing agreement, Pentagon spokesman Col. Steve Warren said.

That said, the intelligence gathered through the surveillance flights is being fed to an interdisciplinary team on the ground, and that team is analyzing it and providing advice to the Nigerian government, he said.

Warren added that the manned and unmanned aircraft being used are unarmed.

Pressure to find the girls

Wednesday marked one month since the 276 girls were abducted from Chibok by Boko Haram. A worldwide campaign to "bring back our girls" has spread awareness of the incident, and as the days go by, the pressure to find them steps up.

U.S. Sen. John McCain, R-Arizona, is among those who support American military intervention to find the girls, if needed.

"You know, it's interesting to me that when a ship is hijacked and taken into custody by these pirates, we have ... no reservations about going in and trying to take that ship back and the crew that's being held," he said. "We have no compunctions about that."

When it comes to the hundreds of girls who were kidnapped, the response has been dragging, he said.

A U.S. military operation "could be done in a way that is very efficient, but for us not to do that, in my opinion, would be an abrogation of our responsibilities," McCain said.

Two senior administration officials told CNN that it is premature to talk about a special operations incursion into Nigeria because the girls have not been found yet.

The U.S. military is there to advise and assist, but not to actively participate, the sources said.

If the girls are found, it would be up to the Nigerians to devise a plan and execute it with U.S. assistance, the sources said.

And that raises other complications.

The Nigerian military is capable of carrying out a rescue operation, but there are concerns because it has been heavy-handed in the past and killed many civilians, the sources said.

As it currently stands, U.S. law prohibits the U.S. military from working with Nigerian military units that have been accused of abuses, a senior State Department official said.

"We've been very clear about our concerns about the Nigerian reports of and evidence of abuses by the Nigerian military," the official said.

Even with all of these complications, the U.S. is committed to doing everything it can to find the girls, the official said.