The U.S. and Nigeria have no "good evidence" about the fate of more than 270 girls who were kidnapped from a boarding school in Chibok, Nigeria, last year by the terrorist group Boko Haram, National Security Advisor Susan Rice said on Wednesday.

"I wish I could give you a definitive answer" about where they are, Rice said during a briefing about President Obama's pending trip to Africa. But she added that "none of us are able to say with certainty what the circumstances of the Chibok girls are today."

Obama just hosted newly elected Nigerian President Muhammadu Buhari at the White House on Monday, and the two leaders discussed the on-going effort to recover the girls and counter Boko Haram, among other things.

"We have been working intently" with regional and global partners to "provide whatever support we could to help locate the girls," Rice said about what the U.S. has done since the girls were abducted. She expects those efforts to "intensify" now that Buhari is in office, she said.

The White House suspended military training to Nigeria's forces over human rights concerns during the administration of Buhari's predecessor, Goodluck Jonathan, but is now resuming that training. The U.S. has continued flying surveillance missions and is providing other expertise to help track the group since the girls disappeared.

Finding the girls is a "very heartfelt priority … but I don't have any good information about leads about their whereabouts," Rice conceded.