Boris Johnson has served Christmas lunch to British troops during a visit to a Nato mission in Estonia on Saturday.
Visiting the Tapa military base near Tallinn, Mr Johnson wished them a merry Christmas as he dished up the meals.
The 850 British soldiers based there represent the UK’s largest operational deployment in Europe.
Later, Mr Johnson will stress the UK’s commitment to Nato and its defence of Estonia’s eastern border with Russia.
The UK is playing a leading role in the alliance’s Baltic mission.
The troops, from the Queen’s Royal Hussars, head the Nato battle group in Estonia, working alongside the country’s troops and personnel from France and Denmark.
Mr Johnson will also tour the military base during his trip.
“I’m here to support our troops because they’re doing an amazing job,” said Mr Johnson from the base.
“The UK is providing the guarantee of the security for the whole continent and particularly here in Estonia.”
Asked if he would be looking at how the Ministry of Defence spends its money, Mr Johnson replied: “I’m a big supporter of our armed forces – I think they do a massive amount of good around the world.
“Obviously we do that in an efficient way but as you know we’re increasing our budget by £2.2 billion – you know about all the investments that we’re making in our armed services. Those will continue.”
Downing Street said it was an opportunity for him to personally thank them for their service and make clear the government’s commitment to support those on the frontline.
During a four-month deployment earlier this year, a squadron of RAF Typhoon jets were scrambled 21 times to intercept 56 Russian aircraft which had strayed into Estonian airspace.
The PM was greeted by his Estonian counterpart Jüri Ratas during the visit. He will stress the role the UK is playing in reassuring its allies and deterring Russian aggression against its Baltic neighbours.
“This year our military efforts in Estonia have been immense,” Mr Johnson said, ahead of the visit.
“So 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 – be it the Baltics, Ukraine or Afghanistan – and those in Britain too.”
The UK is one of the few Nato countries that meets the commitment to spend at least 2% of national income on defence.
The armed forces were given an extra £2.2bn in September’s spending review when Chancellor Sajid Javid announced a 2.6% increase in defence funding in 2020-1.
But a prolonged squeeze on defence spending between 2010 and 2015 has prompted questions about whether the UK is adequately equipped to meet future security threats.
In February, the Public Accounts Committee, the House of Commons’ spending watchdog, reported that the MoD faced a £7bn black hole in its 10-year-plan to equip the armed forces.
In a BBC interview on Thursday, Defence Secretary Ben Wallace said there was a shortfall of funding in the MoD’s budget and confirmed he had recently met with Mr Johnson’s chief adviser Dominic Cummings about improving the way the department spends its money.
Mr Wallace told the BBC’s Political Thinking Podcast that technological advances would change the way the UK bought and built equipment, adding his job was to “manage expectations and say to the [services] chiefs that your appetite has to match your stomach”.