Boris Johnson has served Christmas lunch to British troops based in Estonia on a one-day visit to the Baltic country.
Mr Johnson thanked the servicemen and women for their work as he joined them for lunch at the Tapa military base near the capital Tallinn.
The base hosts 850 British troops from the Queen's Royal Hussars who lead the NATO battlegroup along with personnel from Estonia, France and Denmark.
It is the UK's largest operational deployment in Europe and forms part of NATO's Enhanced Forward Presence in the region.
The prime minister posed for selfies with some of the soldiers before donning a red apron and asking: "Who wants turkey?"
He then asked them to form an orderly queue as he served up the festive lunch of turkey and Yorkshire puddings.
Mr Johnson ate some chocolate cake while sitting down at a table where he chatted to troops about rugby, Russia and the two-can alcohol restriction at their base.
He told them: "Last time I was here, they let me drive a tank. That didn't seem to be on the agenda today."
The prime minister thanked the troops for their work and told them: "In the course of the next few days, everybody in our country is going to be celebrating Christmas with their families and you're going to be here - a long way away, a pretty cold place...
"What you're doing is incredibly important because the reason everybody in our country can have Christmas in peace and security is because of what you're doing here.
"What you're doing is showing that NATO works and that NATO is an alliance to which we in this country are absolutely committed too."
Mr Johnson said the troops were the "most vivid and powerful possible symbol and expression" that Britain is committed to the security and stability of the whole of Europe.
"It's an incredible thing for me to come to Estonia because, when I was a kid - when I was your age - Estonia was part of the Soviet Union and we're now here helping to protect Estonia's security.
"It's a fantastic thing and it's a deeply moving thing for someone from my generation."
He added: "Thank you very much for what you're doing. I hope you have a very, very peaceful, happy time and have a happy Christmas everybody."
After the speech, Mr Johnson posed for photographs with troops beside a Challenger 2 battle tank named after his hero, Winston Churchill, who was in the Hussars.
A Downing Street spokeswoman said the prime minister also held a bilateral meeting with his Estonian counterpart, discussing security and defence.
She said: "The prime minister met Prime Minister Juri Ratas of Estonia today, during a visit to meet British troops stationed in the country over Christmas.
"He thanked Prime Minister Ratas for the support and hospitality Estonia has shown in hosting British Armed Forces personnel at the Tapa military base.
"The leaders discussed the close partnership between the UK and Estonia, in particular our joint security and defence co-operation. The prime minister reaffirmed the UK's unconditional commitment to Estonia's regional security through NATO.
"The two leaders discussed the need to work together to address shared global challenges and the prime minister invited Prime Minister Ratas to attend the COP26 climate change summit in Glasgow next year."