The top US commanders of a coalition base in southern Afghanistan “failed to take adequate force protection” measures prior to a September 2012 attack by the Taliban that led to the deaths of two Marines and the destruction of military aircraft, according to a report on the incident.

Marine Commandant General James Amos fired the two senior commanders of the base at the time, Major General Charles Gurganus and Major General Gregg Sturdevant, essentially forcing them into retirement. The investigation was directed by Army General Lloyd J. Austin III, who leads Central Command, to determine any potential accountability for the attack.

Fifteen Taliban insurgents, dressed in US Army uniforms, went undetected as they breached the eastern perimeter of the complex, and then split into three separate teams to conduct the assault on the base.

According to the report, Gurganus, who maintained overall command of security at the American base, “knew, or should have known” about persistent risks to the compound’s security, and “underestimated the threat posed by the enemy’s capabilities.” Several factors, from inadequate patrolling of the base perimeter, to a faulty assessment of the threat posed by potential enemy infiltrators, contributed to security shortcomings at the complex, the report said.