Since 1969, the UK has had a submarine on patrol for every minute of every day, providing the UK’s nuclear deterrent and this Christmas is no different.
The Armed Forces will also be busy at home.
More than 1,000 personnel are on short notice to react in the UK, with many more deployed around the world.
The Squadrons of the UK’s Quick Reaction Alert will be on duty at RAF Lossiemouth and RAF Coningsby, many of them ready in their green flight suits waiting for the call to scramble and protect UK airspace.
Also on duty will be troops of the Household Division, keeping guard outside royal residences in London and Windsor.
In Europe, 150 UK personnel are deployed to Poland and around 850 British personnel from 1 YORKS are deployed in Estonia on NATO’s Enhanced Forward Presence (eFP) deployment.
In Africa, the 120 Army troops are deployed to wildlife reserves in Malawi to assist local forces with counter-poaching and halt the population decline of many of Africa’s animals, including elephants, rhinos and lions.
Troops will also be in peacekeeping missions in Somalia and South Sudan.