The controversial strategy haunting Afghan war allies

UK Defence Secretary Ben Wallace is looking into accusations that British troops killed unarmed civilians

Sergeant Jay Kenney, 26, with the 101st Airborne Division, Task Force Destiny, assists wounded Afghan National Army (ANA) soldiers off the Blackhawk UH-60A helicopter after they were rescued in an air mission in Kandahar on December 12, 2010 in Kandahar province, Afghanistan. Getty Images

An Afghan Northern Alliance fighter mans the front line against the Taliban on October 2, 2001 near Jabul os Sarache, 30 miles north of Kabul. Getty Images

Abdullah Abdullah, chief executive of Afghanistan travelling via helicopter for the final campaign rally in Bamiyan, Afghanistan on September 25, 2019. Afghans will head to the polls on Saturday, September 28th. Getty Images

Mustafa Tamanna, 10, son of Afghan reporter Zabihullah Tamanna, weeps during the funeral ceremony in Kabul, Afghanistan on June 7, 2016. Tamanna was killed by a rocket-propelled grenade fired by the Taliban. Getty Images

Northern Alliance soldiers come back from the front line after a battle near Charatoy town in the north of Afghanistan on October 10, 2001. REUTERS

A Northern Alliance fighter throwing rocks as part of a popular national game yards away from a multiple Grad missile launcher in October 12, 2001 in the Salang Gorge in Northern Afghanistan. Getty Images

A French soldier from the 7th Mountain Regiment, part of the International Security and Assistance Force (ISAF) stands on a boulder overlooking Kabul during a patrol August 3, 2002 in Afghanistan. The ISAF has been patrolling Kabul since January 2002, working with the government and a new police force to prevent the violence and lawlessness that threatened to engulf the city after a U.S.-led coalition forced the Taliban from power. Getty Images

US Marine Sgt. Jerry Brown (L) of Jacksonville, North Carolina watches over a weapons cache found during a patrol near the American military compound at Kandahar Airport in January 16, 2002 in Kandahar, Afghanistan. The Marines recovered mortars, rockets, rocket-propelled grenades and artillery rounds discovered in various caches near the base while on the patrol. Getty Images)

Members of the Princess Patricia's Canadian Light Infantry patrol through poppy fields in the village of Markhanai in May 6, 2002 in the Tora Bora valley region of Afghanistan. Getty Images

The United States and Britain on October 7, 2001 launched a first wave of air strikes against Afghanistan. President George W. Bush said the action heralded a "sustained, comprehensive and relentless" campaign against terrorism. REUTERS

A young Afghan girl eats a piece of bread at the Chaman refugee camp on November 8, 2001 on the Pakistan border with Afghanistan. The UNHCR has estimated that since September 11, 2001 over 135,000 Afghans have crossed the border into Pakistan, adding to the already millions of refugees living in the country. Getty Images

Afghan opposition Northern Alliance soldiers leap over a trench as they return from front line positions after battle near the town of Charatoy in the north of Afghanistan October 10, 2001. REUTERS

An Afghan child peeks out from the doorway of his family's home as a US Army soldier from the 101st Airborne stands guard in the eastern Afghan village of Hesarak on July 16, 2002 during what the Army refers to as a 'sensitive site exploitation' mission or 'SSE'. Getty Images

Fred Perry, a British Royal Engineer soldier, reads the book "Black Hawk Down" inside his tent after a day of work on January 29, 2002 at the International Security Assistance Force (ISAF) barracks at the Kabul airport in Kabul, Afghanistan. Getty Images

Afghan soldiers (L) speak to a local Afghan, while a medic in the U.S. Army's 1st Battalion, 36th Infantry Regiment, Charlie Company (R) monitors a soldier who has just survived a blast from an improvised explosive device (IED) while driving a vehicle during a mission near Command Outpost Pa'in Kalay, on March 19, 2013 in Kandahar Province, Maiwand District, Afghanistan. Getty Images

Marines on a light armored vehicle prepare for patrol as an AH1W "Super Cobra" helicopter flies by on December 28, 2001 at the U.S. Marine Corps Base in Kandahar, Afghanistan. Getty Images

A Norwegian ISAF (International Security Assistance Force)soldier from Recce Squadron 3 patrols on October 4, 2004 in Kabul, Afghanistan as election officials get ready for the Presidential elections. Getty Images

Interim Afghan leader Hamid Karzai (L) is greeted by a group of Afghan military officers on his arrival to Kandahar airbase on May 04, 2002 in Southern Afghanistan. Getty Images

Soldiers in the U.S. Army's 101st Airborne Division wade though a creek to avoid buried insurgent bombs while on patrol October 16, 2010 in Zhari district west of Kandahar, Afghanistan. Getty Images

British commandos descend from a mountain observation post overlooking the beginning of the Helmand River at the Kajaki hydroelectric dam on March 13, 2007 in Afghanistan's southern Helmand province. Getty Images

101st Airbornes 1st Sgt. Kerry Black from Westmoreland, Tennessee uses an Afghan child's sling shot on February 6, 2002 as children crowd around him while he patrols on the outskirts of Kandahar, Afghanistan. Getty Images

Marine Cpl. Jonathan Eckert of Oak Lawn, IL attached to India Battery, 3rd Battalion, 12th Marine Regiment works his improvised explosive device (IED) sniffing dog Bee as they secure a compound during a patrol near Forward Operating Base (FOB) Zeebrugge on October 11, 2010 in Kajaki, Afghanistan. Getty Images

Afghan refugees walk across the border into Pakistan on October 11, 2001 as they leave Afghanistan at the Chaman crossing point on the 4th day of U.S.-led air strikes against the ruling Taliban and terrorist networks in the country. Getty Images

Anti-Taliban Afghan fighters watch several explosions from U.S. bombings in the Tora Bora mountains in Afghanistan on December 16, 2001.

British Marines run under fire from the Taliban during a morning operation on March 18, 2007 near Kajaki in the Afghan province of Helmand. Getty Images

Afghan Army troops prepare to board a British chinook helicopter from their base at Shorabak on March 12, 2007 in Southern Helmand province, Afghanistan. Getty Images

British Marine Joe Harvey from Stafford, England (R), watches as British forces come under fire by Taliban insurgents on March 18, 2007 near Kajaki in the Afghan province of Helmand. Getty Images

U.S. Army 101st Airborne 3-187 "Bravo" company soliders pass through a corn field while conducting a sensitive site exploitation (SSE) mission July 23, 2002 near the town of Narizah in Southeastern Afghanistan. Getty Images

Scouts from 2nd Battalion, 503rd Infantry Regiment (Airborne), pull overwatch during Operation Destined Strike while 2nd Platoon, Able Company searches a village below the Chowkay Valley in Kunar Province, Afghanistan on August 22, 2006. US Army

A deepening controversy in the UK over accusations that British special forces deliberately killed defenceless Afghan civilians has added to the haunting legacy of the US-led coalition in the long conflict in Afghanistan.

In more than a decade of fighting against the Taliban-led insurgency, with over 3,500 US and allied troops dying and thousands more injured, the role of some soldiers in a “kill or capture” policy against the militants has increasingly become a legal and political battlefield.

British Defence Secretary Ben Wallace has now become involved in the continuing re-examination of the strategy, specifically over allegations that a rogue unit in Britain's elite SAS regiment had killed unarmed civilians during night-time raids in Afghanistan.

An inquiry conducted by the Royal Military Police into the claims closed this year due to lack of evidence.

But secret emails in which British commanders express disquiet about the conduct of an SAS unit in the country have since been revealed.

They emerged from a judicial review of the case brought in London by an Afghan man who claims his father was unlawfully killed by British forces during operations in Helmand province in 2011.

In one email, a senior officer reports "concerning" conversations he had with other commanders, which suggested the existence of "possibly a deliberate policy among the current (redacted) Squadron to engage and kill fighting-aged men", even when they did not pose a threat.

Internal inquiry ordered

Mr Wallace, who continues to insist that SAS units were not involved in unlawful killings in Afghanistan, has now ordered an internal inquiry into why the emails were not previously disclosed to British ministers.

Under the policy, which was implemented in 2010 as part of the “surge” strategy devised by coalition commander US General David Petraeus, teams of special forces drawn from western countries taking part in the Nato mission were sent to destroy the Taliban’s leadership.

Defence secretary Ben Wallace is now involved in the appraisal of the UK's controversial military strategy in Afghanistan. EPA

In particular, teams of special forces from countries including the US, Britain, Australia and New Zealand were given the task of targeting the Taliban fighters responsible for deadly attacks against coalition forces using improvised explosive devices.

It has subsequently been revealed that Iran’s Islamic Revolutionary Guard Corps helped to provide the Taliban with IEDs, which were responsible for many of deaths and serious injuries sustained by coalition forces.

While the coalition policy ultimately succeeded in putting the Taliban on the defensive, 10 years on it is increasingly a source of controversy over claims that some of those killed during the special forces’ raids were unarmed civilians, and not Taliban combatants as was originally claimed.

Public apology for civilian killings

Last week the chief of the New Zealand Defence Force was obliged to make a public apology after a damning report into its operations in Afghanistan found that civilians, including a child, had most likely been killed during an operation in August 2010, and that officials had tried to cover up the facts for seven years.

In Australia, meanwhile, a member of the country’s elite Australian SAS Regiment has been suspended from duty after footage emerged of an unarmed Afghan man being shot dead at close range in Uruzgan province in 2012.

The soldier claims he acted in self-defence, but Australia’s Department of Defence has issued a statement saying the allegations are “serious and disturbing".

While the coalition’s military campaign in Afghanistan may have ended, the controversy over the tactics used against the Taliban is far from over.