The Prime Minister has visited more than 800 British troops based in Estonia to thank them for their service over the Christmas period.
Boris Johnson served a Christmas lunch to soldiers at Tapa military base near Tallinn.
850 British troops from the Queen's Royal Hussars are currently deployed to the country as part of NATO's Enhanced Forward Presence mission.
Speaking ahead of the visit, Mr Johnson said: “The men and women of our Armed Forces serve tirelessly every single day to keep us all safe.
"While we enjoy Christmas with family and friends, they will be working hard across the world to defend Britain and our allies."
"At this time of year, we should all take a moment to be thankful for the sacrifices made by our troops, many of whom will be spending Christmas on our deployments and bases around the world."
The soldiers also gave Mr Johnson a tour of the base's facilities, including a hangar where he saw tanks and other military vehicles.
He also held a meeting with his Estonian counterpart, Jüri Ratas.
The troops stationed in the country make up the UK's largest operational deployment in Europe - leading a NATO battlegroup made up of Estonian, French and Danish personnel.
The NATO mission, designed to deter potential Russian aggression, also has a presence in other Eastern European nations including Latvia, Lithuania and Poland.
Between May and September, an RAF Typhoon squadron was also deployed to Estonia to help protect the country's airspace.
The fighter jets conducted 21 interceptions of 56 Russian aircraft over the four-month deployment.