The State Department acknowledged Thursday it could have acted sooner to designate Nigeria’s Boko Haram a foreign terrorist organization, even though the Nigerian government and many Africa experts opposed the move when it was first considered two years ago.

The acknowledgment — accompanied by a caveat that it is impossible to say if an earlier designation would have had a significant impact on the group — came amid Republican criticism of former Secretary of State Hillary Rodham Clinton’s decision not to take the step in 2012. And it was made as senior U.S. officials declared to Congress that freeing the schoolgirls abducted by the radical Islamist group last month has become one of the Obama administration’s top priorities.

As the 276 girls entered a second month in captivity that has sparked global outrage, senior officials from the State Department, the Pentagon and the U.S. Agency for International Development told a Senate Foreign Relations subcommittee that the U.S. is committed to assisting Nigeria in combatting the al-Qaida-linked Boko Haram as it expands its reach and builds capacity for more sophisticated and deadlier terror attacks.

At the same time, though, the officials lamented limitations on U.S. cooperation with the Nigerian military due to its poor human rights record. And they expressed concern about the Nigerian government’s commitment to fight the group and the ability of its army to do so.

“In general, Nigeria has failed to mount an effective campaign against Boko Haram,” said Alice Friend, the Defense Department’s principal director for Africa. “In the face of a new and more sophisticated threat than it has faced before, its security forces have been slow to adapt with new strategies, new doctrines and new tactics.”

Robert Jackson, a State Department specialist on Africa, told the panel that Nigerian objections to the State Department formally listing Boko Haram a “foreign terrorist organization” in 2012 were a main reason Clinton chose not to make that designation, which would have imposed sanctions.

At the time, some U.S. agencies, including intelligence services and the Justice Department, were pushing for the designation, saying the group met the strict criteria and was becoming a growing threat, not only to Nigerians but to U.S. interests in west Africa.

The Nigerian government, however, argued that such a designation could give undeserved visibility and credibility to what was then a largely localized insurgency.

After what Jackson called a “healthy debate,” Clinton opted to blacklist Boko Haram’s top three commanders as individual terrorists instead of designating the entire group.

It was not until last year, under current Secretary of State John Kerry, that the State Department listed Boko Haram as a terrorist organization. The administration has also offered a reward of up to $7 million for information leading to the capture of its leader.

Asked by Sen. Marco Rubio, R-Fla., if that had been a mistake to wait, Jackson said the U.S. might act more quickly and be less deferential to foreign governments’ desires in the future.

“In retrospect, we might have done it earlier,” he said, adding: “I think the important thing is that we have done it and that we’ve offered a reward for the leadership of Boko Haram’s location.