As NATO prepares to celebrate its 70th anniversary this week, Forces News has been given special access to Imjin Barracks - one of Britain's leading contributions to the alliance.
The Gloucestershire barracks are home to the Allied Rapid Reaction Corps, known as 'ARRC'.
From Kosovo, to Bosnia and Afghanistan, NATO’s ARRC is made up of top military minds from more than 20 different countries, charged with leading and delivering NATO’s missions on the ground, always on high readiness to respond to emergencies.
If the ARRC are called into an operation, they can call on a pool of soldiers from across the alliance.
Now they are preparing for an even greater role which would see them being able to command up to 120,000 troops - something not planned for on this scale since the Cold War.
What will it mean in practice?
Major General Jez Bennett, Chief of Staff, Allied Rapid Reaction Corps, said:
"In practice it means that NATO is saying there is a risk again of a significant conflict in Europe.
"And that it needs to have the means to deter that conflict from happening, and to prevent it from happening, if necessary.
"As ever, it depends on where it happened, and when it happened. Our focus, I think, at the moment is in Europe. So, of course, World War Three could break out anywhere and I think NATO's focus is largely on the NATO members which is largely focused on the North Atlantic, as the name implies.
"But in the event that something of that scale were to happen in the next couple of years, then I would envisage the ARRC being at the forefront of the land answer to it.
"It certainly appears that we are looking at that [something on a much bigger scale than we've seen since the Cold War] as a potential outcome.
"That is certainly nothing that people want to happen.
"But as ever with things, if you're prepared for it, the likelihood of it happening is reduced."
Brigadier General David Hamilton is Deputy Chief of Staff for Operations, Allied Rapid Reaction Corps, said: "Internationally, I think everyone's looking at the 70th [anniversary] and recognising the tremendous achievements of NATO historically - with an eye to the future to determine what the significance of NATO and the alliance will be to face the new challenges we have.
"I think what NATO's first thought is 'how do we promote peace?'
"I think that's what the purpose of the alliance is - to promote security for its partners and to be a deterrent for those who might consider other options than peace."
It is not clear what challenges face the alliance over the next 70 years, but the ARRC’s new enhanced role in NATO places the UK at the forefront of the alliance’s plans for how it will respond to whatever lies ahead.