Taliban fighters don't have to look too hard to find their government enemies.
Militants kidnapped the professors in Kabul in an August raid.
Many U.S. officials favor greater cooperation with Pakistan to combat militancy, while others urge a tougher approach.
Tora Bora, an underground complex of fortified caves that once protected Al-Qaeda chief Osama bin Laden, is now in the hands of the Islamic State militant group.
An official said no immediate decision had been made about future troop numbers, which are now set at about 8,400.
The U.S. military command in Kabul said it was investigating the reports.
The Taliban claims the attacker, who was killed, as a member.
Two troops also were wounded when an Afghan commando opened fire.
The Army will send 1,500 paratroopers from the 1st Brigade Combat Team, 82nd Airborne Division to "train, advise and assist" in Afghanistan.
The report comes as Afghan officials prepare to face a review of the country's record of implementing anti-torture laws.
The U.S. military's biggest conventional bomb may have struck the Islamic State group in Afghanistan, but it missed the target on stopping the Taliban takeover.
A ministry spokesman said no civilians were harmed in Thursday's massive blast that targeted a network of caves and tunnels.
The U.S. has said it will not attend Moscow-led peace talks scheduled for Friday.
A jury found Ibrahim Suleiman Adnan Adam Harun, known by the nom de guerre Spin Ghul, guilty of all counts.
Elite forces freed 32 people imprisoned by the extremist group in Helmand province.
Votel said a strategy was still being developed and did not give details on the number of troops that would be required or when a final decision would be made.
The attackers were reportedly wearing white doctors' coats.
Attacks on health care facilities have resulted in an increase in deaths from preventable diseases, the report says.
Four civilians and three soldiers died in Lashkar Gah.
Afghan civilian casualties reached a 15-year high in 2016, according to the U.N.