A former Chief of the Defence Staff has described the decision to draft in reservists should the UK crash out of the EU without a deal, as a "belt and braces measure".
In the case of a no-deal, a new order confirmed the Ministry of Defence (MOD) can call upon reserves.
As many as 3,500 personnel could be called up, with around 10% of those being reservists - a decision which General Lord Richards described as "sensible".
The move will enable commanding officers to send 'call out' notices to personnel if requested by government departments.
Speaking to Forces News, General Lord Richards explained why it makes sense for reservists to help.
"Amongst the reserves there are some pretty rare capabilities that the regular Armed Forces might only have in small numbers so you can draw civilian skills in more readily this way," he explained.
"If I was in the Government, I would have this up my sleeve, too. It doesn't mean they'll be deployed...but I think it's a sensible measure."
The last time the Armed Forces were used on a large scale civilian operation was the London Olympics in 2012, General Lord Richards was the Chief of the Defence Staff at the time.
General Lord Richards said a no-deal call out order would be smaller than that of London 2012 but admitted it carries different challenges.
He said the possibility of "social disorder" following Brexit is becoming a greater "worry", adding the Armed Forces "would be very, very reluctant to become involved".
"I don't see that it's (social disruption) likely," General Lord Richards said.
"But if one or two of the doom-mongers are to be believed and the scale of social disorder, say in the failure to come out of the EU...you only need a couple-of-hundred-thousand - a small proportion to act up and the Police could have a problem.
"But I think that is one end of the spectrum, I don't see that is likely."
General Lord Richards added he has "no doubt" that the Armed Forces have already been doing some planning ahead of a no-deal scenario.
Any reservists who are mobilised for full-time service will be sent a 'call out' notice.
In most cases, personnel get 28 days' notice upon receiving a 'call out', however this may decrease in urgent situations.
When asked how long could the Armed Forces sustain working alongside civil authorities, General Lord Richards said: "The Armed Forces are too small, they are well below the level they're meant to be at.
"That's one reason why the reserves have been called out...and I think we could go on doing it for a while."