Two RAF Typhoons have arrived in Estonia as part of Britain's contribution to NATO's mission to reassure allies in the Baltic states.
They'll join hundreds of British personnel already in Estonia, where the UK is leading one of four NATO multinational units.
Other nations are deploying to Latvia, Lithuania and Poland.
Defence Secretary, Sir Michael Fallon announced the deployment last year, amid growing concern over Russia, following the annexation of Crimea from Ukraine in 2014.
"Since last year's Warsaw Summit, the UK is stepping up its commitment to NATO, nowhere more clearly than in the Baltic States"
Minister for the Armed Forces Mark Lancaster TD MP travelled to Estonia to greet the pilots and the ground crew. He said:
"The NATO presence on land, sea and in the air is vital to secure peace and prosperity.
"We are here standing shoulder to shoulder with our allies in the face of any potential threats, thereby demonstrating our continuing commitment to the security of Europe."
Squadron Leader Paul Hanson, one of the Typhoon pilots, said the mission shows how air power can reassure allies:
"This deployment proves our ability to move fast jets from NATO's south eastern flank to the Baltic region in a matter of hours."
The RAF jets will train and work with British and Estonian personnel on the ground, as NATO steps up its mission in the region.