An American flag flies at half-staff in front of a Realtors office in honor of the fallen Navy SEALs based at nearby Naval Amphibious Base Little Creek in Virginia Beach, Va. (Mark Wilson/GETTY IMAGES)

A U.S. military investigation has concluded that the August helicopter operation in which 30 Americans and eight Afghans were killed in one of the deadliest missions for U.S. troops since the beginning of the Afghan war was soundly planned and executed.

The findings, which U.S. Central Command released Wednesday night in a five-page executive summary, defended a decision by commanders to load all of the 17 Navy SEALs and their support personnel onto one helicopter.

The SEALs were dispatched to the Tangi Valley in eastern Afghanistan after an initial assault on the area by a platoon of U.S. Army Rangers and Afghan forces who had been sent to capture or kill Qari Tahir, the leader of Taliban forces in the area. About three hours after the Rangers attacked Tahir’s compound, U.S. surveillance aircraft spotted nine or 10 suspected fighters walking in the woods about 1.5 miles from the initial target site.

The U.S. commanders overseeing the operation thought the Taliban leader might be among them and sent SEALs after the group. The American commander decided to put all of the SEALs and support personnel on one aircraft so the SEALs would be able to strike the enemy faster with more troops, the report says. The commander also concluded that the second helicopter that moved into the area would be under increased risk as it approached the landing zone because it would not have had the element of surprise.

The report, written by Army Brig. Gen. Jeffrey N. Colt, described that decision as “tactically sound.”

Colt found only minor fault with one aspect of the operation. As the SEALs were approaching the landing zone, commanders chose not to reallocate airborne surveillance assets in the area.

About one minute before landing in the Tangi Valley, the helicopter with the SEALs descended to 100 to 150 feet and slowed to 58 mph. “A previously undetected group of suspected Taliban fighters fired two or three [rocket-propelled grenades] in rapid succession from the tower of a two-story mud-brick building about 220 meters south” of the Chinook helicopter, the report says.

The second rocket-propelled grenade struck one of the helicopter’s rotors, causing the loss of more than 10 feet of blade. The report emphasizes that the crash was not the result of the commander’s decision not to shift the surveillance planes.

According to the findings, “the shoot down was not the result of a baited ambush, but rather the result of the enemy being at a heightened state of alert due to 3 1 / 2 hours of ongoing coalition air operations concentrated over the northwestern portion of the Tangi Valley.”

The report says that commanders should make a better effort to reallocate and synchronize surveillance aircraft before sending a helicopter to area with enemy activity. The helicopters are most vulnerable just before landing and after taking off.

The report praises the soldiers who were flying the Chinook when it crashed. “The crew pairing reflected a conscious command effort to mitigate risk by using the best possible crews available,” it says.

The Taliban leader who was targeted in the initial assault was killed by U.S. forces in a later mission.