LONDON >> British lawmakers said Wednesday that U.K. commanders’ complacency and inadequate security were partly to blame for the failure to stop a Taliban attack on a U.S-British base in Afghanistan that killed two U.S. Marines.

The House of Commons Defense Committee said more than half the guard towers were unstaffed at the time of the audacious September 2012 assault on Camp Bastion in Helmand province.

The lawmakers said troops on the base — who at the time included Prince Harry, a helicopter pilot — had been exposed to “unnecessary risk.”

“Insufficient attention was given to the fundamental requirement of defending Camp Bastion from external assault,” they said in a report. “We believe that this was complacent.”

The committee also said the Ministry of Defense had been “obstructive and unhelpful” toward lawmakers investigating the attack.

In the attack, 15 Taliban insurgents dressed in U.S. military uniforms and armed with rocket-propelled grenades cut through perimeter wire.

In the ensuing firefight, two Marines were killed and 17 American and British personnel injured. Six U.S. Harrier jump jets valued at almost $200 million were destroyed.

Two American generals were forced to retire after a U.S. investigation into the incident.

Since the attack took place in the British sector of the camp, the lawmakers said that “British commanders must bear a degree of responsibility for these systemic failures.”

Defense Secretary Philip Hammond said “U.K. commanders have identified and acted upon all lessons following the attack on Camp Bastion in 2012.”