Less than two years after it blocked a sale of American-made attack helicopters to Nigeria from Israel because of human rights concerns, the United States is poised to sell up to 12 light attack aircraft to Nigeria as part of an effort to support the country’s fight against the Boko Haram insurgency.

The Super Tucano, a turboprop aircraft, is designed for light attack, counterinsurgency, close air support and reconnaissance missions. It could prove useful as the Nigerian military tries to clear Boko Haram out of the Sambisa Forest, which is believed to hold large numbers of the militants, as well as kidnapped girls and women.

The New York Times reported that the pending sale of the Super Tucano attack warplanes — which would require congressional approval — is already coming under criticism from human rights organizations that say President Muhammadu Buhari has not yet done enough to stop the abuses and corruption that flourished in the military under his predecessor, Goodluck Jonathan.

The paper reported that officials at the White House, the State Department and the Pentagon have been bracing for a fight with congressional Democrats, in particular Senator Patrick J. Leahy of Vermont, who sponsored a bill to block the sale of military hardware to countries whose military have poor human rights record.

The proposed sale reflects the warming of the relationship between the Nigerian and American militaries, which had frayed under Mr. Jonathan. The Pentagon often bypassed Nigeria in the fight against Boko Haram, choosing to work directly with neighboring Cameroon, Chad and Niger.

In addition to citing corruption and sweeping human rights abuses by Nigerian soldiers, American officials were hesitant to share intelligence with the Nigerian military, saying Boko Haram had infiltrated it. That accusation prompted indignation from Nigeria.

But that was before Buhari, a former Nigerian Army major general, came to power. Since coming into power in May last year,  Buhari has devoted himself to fighting graft in Africa’s largest economy.

He has fired a number of Nigerian military officers accused of corruption, and American military officials say they are now working closely with some of their counterparts in Nigeria. The Obama administration is also considering sending dozens of Special Operations advisers to the front lines of Nigeria’s fight against Boko Haram, an insurgency that has killed thousands of civilians in the country’s northeast as well as in Cameroon, Chad and Niger.

The US may be encouraged by the Buhari administration’s pledge to investigate allegations of human rights abuses and his promise not to tolerate them.

It is believed that the US government may send a formal notification to Congress on the sale of the attack aircrafts before July when President Obama is expected to visit Nigeria.

“The United States is committed to working with Nigeria and its neighbors against Boko Haram,” said David McKeeby, a spokesman for the State Department’s Bureau of Political-Military Affairs. “The Nigerian security forces and regional forces from Cameroon, Chad and Niger have made important progress in pushing Boko Haram out of many towns and villages of northeast Nigeria and the broader Lake Chad basin region.”

Consideration of selling the attack aircraft to Nigeria is a sharp turnabout from two years ago, when the United States blocked the sale of American-made Cobra attack helicopters to Nigeria from Israel, amid concerns about Nigeria’s protection of civilians when conducting military operations. That infuriated the Nigerian government, and Nigeria’s ambassador to the United States responded sharply, accusing Washington of hampering the effort against Boko Haram.

Under the Jonathan administration,  the Nigerian military was accused by human rights groups of detaining and killing thousands of innocent civilians in sweeps of the militant group, a practice that Amnesty International said was continuing. This year the military rounded up several hundred men and boys in arrests that Amnesty, in a report it released last week, called “arbitrary, the hazardous profiling based on sex and age of the individual rather than on evidence of crime.”

The report said 149 people had died this year in detention in the Nigerian military’s Giwa barracks in Maiduguri, a city that has been a staging ground for the fight against Boko Haram. Among the victims were 11 children under age 6, including four infants, Amnesty said. The prisoners most likely died of disease, starvation, dehydration or gunshot wounds, the report said.

In a news release, the Nigerian military called the report “completely baseless, unfounded and source-less with the intent of denting the image of the Nigerian Armed Forces.”

A version of this article appears in print on May 16, 2016, on page A6 of the New York edition with the headline: Push to Sell Planes Shows U.S. Thaw With Nigeria.