UK partly to blame for failure to stop Afghan attack - MPs
British commanders must "bear a degree of responsibility" for the failure to prevent a Taliban raid in Afghanistan in 2012 that left two US marines dead, a group of MPs has said.
The Commons Defence Committee said the UK's main base Camp Bastion had been left vulnerable by a "complacent" approach to perimeter security.
They also criticised the "apparent tolerance of poppy cultivation immediately outside the fence".
Ministers said lessons had been learnt.
But Defence Secretary Philip Hammond denied that the Ministry of Defence was complacent, and said the perceived threat to Camp Bastion at the time of the attack had been relatively low.
Camp Bastion was long seen as almost impregnable: set up in the middle of the desert in Helmand, with good lines of sight. But over the years the camp grew enormously.
The military focus by 2012 was very much on the wider threats to UK and other forces outside the base, but also the "insider threat" from disgruntled Afghan national army or police officers. The threat from a heavily armed insurgent attack on the camp itself was clearly underestimated.
The lesson was costly, above all for the US. Had British lives and equipment been lost to the same degree, the level of censure here might have been more severe.
As it is, British forces say they have indeed learned and implemented the lessons of that attack on Camp Bastion - a camp which is now slowly being dismantled ahead of the Nato withdrawal of combat troops from Afghanistan by the end of the year.
The risks for British and American troops will only increase as their numbers go down at Camp Bastion in the coming months. Afghan forces are expected to take on the running of their part of the camp, while most of the rest of it will be wound down.
Constant vigilance will be required until the final moment, when the last British boots shake off the dust of Helmand.
In its latest report, the committee said more than half the guard towers had been left unmanned, leaving troops exposed to "unnecessary risk".
This included the tower closest to the point where the insurgents broke through the fence, contributing directly to the failure to detect the attack at an early stage, the committee said.'Screwed up'
The MPs accused the Ministry of Defence of being "obstructive and unhelpful" as they sought to establish the circumstances leading up to the attack, denying them access to documents.
In addition to the two US marines who were killed, eight US and eight UK military personnel and a civilian contractor were injured. Six US Harrier jets were also destroyed, and there was significant damage to other vehicles and equipment.
The attack took place on the night of 14 September 2012 when 15 heavily armed Taliban insurgents dressed in US military uniforms cut through the perimeter wire on the eastern sector of the base.
Fourteen of the insurgents were killed in the fighting, and one was captured.
Following a US investigation into the incident, two US generals were forced to retire.
Papers released by the US government showed that US officers had complained that the British had refused to pay for a new security fence following an earlier attempted suicide attack on the runway.
But in October Mr Hammond disputed a US major's claim that the UK forces "knew that they had screwed up".
The committee said: "We were told that the focus of Isaf [International Security Assistance Force, or the Nato-led mission in Afghanistan] commanders had been on security incidents elsewhere in Helmand Province and on threats from insider attack.
"Insufficient attention was given to the fundamental requirement of defending Camp Bastion from external assault.
"We believe that this was complacent. Given that the attack took place in the British sector of the camp, British commanders must bear a degree of responsibility for these systemic failures and associated reputational damage.
"We note the acknowledgement by the MoD that errors were made which, collectively, created the vulnerabilities which were so devastatingly exploited by the enemy. From the evidence we have received, we are satisfied that as far as possible, these vulnerabilities have now been addressed."Poppy cultivation
The MPs had also been "concerned" to learn of a string of breaches of the perimeter fence in the two years before the attack, which were dismissed as "low-level scrapping and criminal activity", with trespassers seeking to steal metal they could sell for profit.
The MPs reported that one senior US commander also said efforts to tackle the poppy cultivation outside the fence had failed "because the Afghans had to do it. We weren't allowed to."
They continued: "We consider that the failure to take concerted action to prevent these activities increased the risk of surveillance and intelligence gathering by Afghan nationals which could have assisted insurgent planning for an attack on the base."
The committee concluded: "We recommend that the MoD capture the lessons identified from this extraordinary attack as part of its wider efforts to learn lessons from Afghanistan for future operations."
Mr Hammond said: "The Ministry of Defence is not complacent and always seeks to capture and learn lessons from current operations.
"Commanders in the field have to prioritise resources against potential threats in theatre and at the time a threat to Camp Bastion was considered to be lower than to other Isaf assets in Helmand. UK commanders have identified and acted upon all lessons following the attack on Camp Bastion in 2012."
He also said "a considerable amount" of classified information had been released to the committee in the course of its inquiry.