RAF fighter jets will deploy to Romania from May as part of Nato efforts to reassure eastern European countries concerned about Vladimir Putin's Russia.
Defence Secretary Sir Michael Fallon said four Typhoons from 3 (Fighter) Squadron will lead the deployment, part of the Nato southern air policing mission.
Sir Michael also confirmed UK investment in developing cyber warfare capabilities and skills, including the ability to launch online attacks.
The Typhoons, from RAF Coningsby in Lincolnshire, will spent up to four months based at Mihail Kogalniceanu airbase in south east Romania, policing the skies over the Black Sea alongside local jets.
Sir Michael had already indicated that RAF jets would join the Nato operation in Romania, but he confirmed the date of the deployment and the squadron at an event in London.
Sir Michael said: "The UK is stepping up its support for Nato's collective defence from the north to the south of the alliance.
"With this deployment, RAF planes will be ready to secure Nato airspace and provide reassurance to our allies in the Black Sea region."
In a wide-ranging speech at the international parliamentary conference on national security, Sir Michael said an already-announced £1.9 billion investment in cyber security would help develop skills and capabilities across government.
He said: "Our military is among the best prepared in the world to tackle cyber threats with capabilities and skills integrated into the Army, Royal Navy, and the RAF. But in such a dynamic environment we must continually test and enhance our skills.
"We're interested not just in defensive but also in offensive cyber, those who threaten cyber-attacks against us need to know the risk they're running."