Probes into alleged misconduct by British troops in Northern Ireland and Afghanistan will not be allowed to turn into "witch-hunts", Sir Michael Fallon has insisted.
The Defence Secretary gave MPs the assurance following widespread concern about the investigations into events in Iraq amid claims that probe had been abused by lawyers and had got out of control.
The Royal Military Police is leading Operation Northmoor, looking into allegations in Afghanistan, while the PSNI is reviewing killings linked to the Troubles.
Concerns have been raised that they could heap further pressure on serving troops and veterans following the controversial Iraq Historic Allegations Team (Ihat) investigation.
Sir Michael told the Commons Defence sub-committee: "Northmoor is already under way, it is a much smaller investigation than Ihat and there are some very specific terms of reference to investigate criminal allegations in regard to the treatment of detainees from the point at which they are captured until they are released or they have been handed over to the Afghan judicial system.
"Ihat, of course is looking right across the field and that's what we don't want to see again. The Northmoor investigation is very specific."
On Northern Ireland, Sir Michael said the PSNI investigation was not something that ministers could control. He explained that the Stormont House Agreement meant "we are now looking at how we can ensure that this process in Northern Ireland is not random, that it is properly proportionate - in other words that murders by terrorists are fully investigated if there are to be investigations into any deaths at the hands of our service personnel".
The Defence Secretary said he will not let either process turn into a "witch-hunt".
"I am not going to see Northmoor develop into a witch-hunt. Obviously the investigation has to be done at arm's-length from the ministry, we understand that.
"It's being done by the Royal Military Police and that's the correct way to do it. But I'm not going to let it descend into a witch-hunt and I am certainly not going to let the Northern Ireland process descend into a witch-hunt." Meanwhile, former Army officer Rachel Webster has called on the Prime Minister to put an end to Ihat.
Ihat has been investigating alleged abuses by UK military personnel against Iraqi civilians dating back more than a decade.
Ms Webster, who rose to the rank of captain and completed four tours of duty in Iraq and Afghanistan, is taking legal action after being targeted by Ihat investigators.
The highly commended officer complains of being roughly treated and humiliated when arrested and physically restrained in her own home in a dawn raid on January 10, 2014.
She called on Theresa May to stop Ihat continuing its operations "to avoid any further damage to military personnel".
She listened as a statement was read out on her behalf on the steps of the Royal Courts of Justice in London, saying: "Christmas is a difficult time for the armed services and their families and this is not helped by the ongoing and unnecessary Ihat investigations.
"Rachel firmly believes that the British armed forces are the best in the world and yet they have faced thousands of unwarranted allegations of criminal conduct."
Soon after the statement was read, Ms Webster, who was wearing her military service medals, broke down in tears.