British troops have arrived in Estonia as part of a major Nato mission in the Baltic states to deter Russian aggression.
Around 120 soldiers from the 5th Battalion The Rifles landed at the Amari airbase on Friday, 25 miles south-west of the capital Tallinn.
They were welcomed by Estonia's defence minister Margus Tsahkna on their arrival from RAF Brize Norton.
Eight hundred British troops are due to be stationed in the country as part of one of the biggest deployments to Eastern Europe in decades.
The first batch will set up a UK headquarters in the country before the rest arrive next month.
They will work alongside French and Danish forces to "provide a proportionate, defensive, and combat capable force to defend our Nato ally and deter any form of hostile activity against the Alliance", the Ministry of Defence said.
Britain is taking a leading role in the Estonia Battlegroup, while other nations are deploying troops to Latvia, Lithuania and Poland as part of Nato's Enhanced Forward Presence battalion.
Around 300 UK vehicles have also left the UK this week by ferry headed for Estonia, including Challenger 2 tanks, Warrior infantry fighting vehicles, and AS90 self-propelled artillery pieces.
Britain and Estonia have a long history of defence co-operation.
In November 1918 a Royal Navy squadron was deployed to the region to support the independence of the Baltic states.
Defence Secretary Sir Michael Fallon said: "In the face of an increasingly assertive Russia, Nato is stepping up its commitment to collective defence.
"British troops will play a leading role in Estonia and support our US allies in Poland, as part of wider efforts to defend Nato.
"Our rising defence budget means we can support those deployments in the long-term and strengthen our commitment to European security."
Lieutenant Colonel Mark Wilson, Commanding Officer of 5th Battalion The Rifles, said: "The UK and Estonia have a long and proud history of serving together, including in Afghanistan, so it is an honour to lead 5 RIFLES on this deployment as part of Nato's enhanced Forward Presence.
"My soldiers are looking forward to again be working, training and exercising alongside their Estonian counterparts."