International forces killed the Taliban insurgents responsible for shooting down a U.S. helicopter and killing 38 U.S. and Afghan forces over the weekend, but they are still seeking the top insurgent leader they were going after in Saturday's mission, the top American commander in Afghanistan said Wednesday.

Marine Corps Gen. John Allen told a Pentagon news conference that an F-16 airstrike Monday took out fewer than 10 insurgents involved in the attack on the Chinook helicopter.

In a separate statement Wednesday, the military said the Monday strike killed Taliban leader Mullah Mohibullah and the insurgent who fired the rocket-propelled grenade at the helicopter.

The military said intelligence gained on the ground provided a high degree of confidence that the insurgent who fired the grenade was the person killed. It did not provide further details.

Allen defended the decision to send in the Chinook loaded with special operations forces to pursue insurgents escaping from the weekend firefight with Army Rangers in a dangerous region of Wardak province of eastern Afghanistan.

"We've run more than a couple of thousand of these night operations over the last year, and this is the only occasion where this has occurred," said Allen.

"The fact that we lost this aircraft is not ... a decision point as to whether we'll use this aircraft in the future. It's not uncommon at all to use this aircraft on our special missions."

While officials believe the helicopter was shot down by a rocket-propelled grenade, Allen said the military's investigation into the crash will also review whether small arms fire or other causes contributed to the crash.

Questions remain about why the troops were called in to aid other U.S. combatants engaged in a firefight, what they knew about the situation on the ground and what role the flight path or altitude may have played in the disastrous crash.

Allen and other officials would not discuss the details of the probe, but it no doubt will include a look at the insurgent threat and the instructions given to the special operations team that crowded into a big Chinook helicopter as it raced to assist other U.S. forces.

According to officials, the team included 22 Navy SEAL personnel, three Air Force airmen, a five-member Army air crew and a military dog, along with seven Afghan commandos and an Afghan interpreter.

Gen. James Mattis, head of U.S. Central Command, appointed Army Brig. Gen. Jeffrey Colt to lead the investigation. Colt is deputy commander of the 101st Airborne Division.

The investigation comes as the remains of the troops killed in the crash were returned Tuesday in an operation shrouded in secrecy by a Defense Department that has refused so far to release the names of the fallen and denied media coverage of the arrival at Dover Air Force Base in Delaware.

Two C-17 aircraft carrying the remains were met by President Barack Obama, Defense Secretary Leon Panetta, the Joint Chiefs chairman, Adm. Mike Mullen, and a number of other military leaders.

The investigation will review a number of basic crash questions, which will probably rule out such factors as the weather, terrain and mechanical issues, since military officials believe the helicopter was shot down. It also will look at the flight of the Chinook as it moved into the fighting zone.

Chinooks are heavy cargo helicopters that do not have the agility of smaller, more maneuverable aircraft.

Meanwhile, the Pentagon said Wednesday that it will release the names of the troops killed — after days of debate and delay.

The release had been in question because the dead were mostly covert special operations forces from the Navy and Air Force.

Though some of their names had been made public by loved ones, the Special Operations Command asked the Pentagon not to release them, arguing it was a security risk.

Pentagon spokesman Col. Dave Lapan said Wednesday Defense Secretary Leon Panetta considered the issue and decided to release the names. Lapan said the names should be made public within 24 hours.

Obama and other officials at Dover boarded the two C-17 aircraft to pay tribute to the fallen troops and then watched as 30 transfer cases draped in American flags and eight draped in Afghan flags were taken off the planes.

There were several additional transfer cases on the planes, also carrying unidentified remains from the crash.