Military personnel from six Joint Expeditionary Force (JEF) nations, including the UK, have conducted 'freedom of navigation' patrols in the Baltic Sea region.
Royal Navy ships HMS Northumberland and HMS Richmond joined vessels from Denmark, Sweden, Estonia, Latvia and Lithuania to escort supply ships delivering military equipment to NATO forces in Estonia.
The warships and aircraft conducted exercises to demonstrate their interoperability – testing how they operate in conjunction with each other while deployed as an alliance.
Watch: What is the Joint Expeditionary Force?
In the skies above the vessels, Danish and Swedish fighter jets rehearsed air defence tactics, while one of the UK's new Poseidon submarine hunter aircraft practised spotting enemy targets.
Major General Jim Morris DSO, the Commander of the UK Standing Joint Force HQ (SJFHQ) which leads JEF, said: "Given the current level of aggression being displayed by Russia, there has never been a more important time to ensure that freedom of navigation is maintained in the Baltic Sea."
JEF is a UK-led force comprising 10 nations working together to deliver defence capabilities at high readiness.
It focuses on security in the Baltic Sea region, the High North and the North Atlantic, where its members are located.
The High North is the territories of Nordic countries – including Denmark, Finland, Iceland, Norway, Sweden – located throughout the Arctic beyond the Polar Circle.
Earlier this month, Prime Minister Boris Johnson hosted a summit of JEF leaders in London where member nations committed to supporting Ukraine with military aid.
Watch: The British military has been doubling its troop presence in Estonia.