Some 4,000 soldiers were in the Baltic Sea region on Sunday for the first day of a nearly two-week-long NATO manoeuvre.
Forty naval unites and 60 aircraft will also take part in the BALTOPS exercise that lasts until 18 June, according to the German Navy Press and Information Centre.
Sixteen NATO members are represented, as well as Sweden and Finland, in the 50th iteration of the BALTOPS exercise.
The exercise will include defensive cyber warfare tactics for the first time.
Finland participates in the exercise with two vessels, Mine Layer Hämeenmaa and Mine Hunter Coastal Vahterpää, according to a press release by the Finnish Defence Forces.
The Finnish troops' objectives of the exercise are developing national defence and enhancing personnel's abilities to act in an international framework. The exercise develops the interoperability between NATO and partner countries' Navies, Air Forces and special forces in the maritime environment.
The Finnish vessels will operate in separate units. Mine Layer Hämeenmaa participates in the surface warfare unit and Mine Hunter Coastal Vahterpää in the mine countermeasures unit, which is led by the Standing NATO Mine CounterMeasures Group 1 (SNMCMG1).
Training with the SNMCMG1 supports Vahterpää's preparations for the NRF-period which is planned for the year 2022.
'Foundation of interoperability'
"This year, we celebrate the 50th BALTOPS, an exercise that sets the foundation of interoperability across the Alliance," said US Vice Admiral Gene Black, the commanding officer.
"Lessons learned in BALTOPS enable international strike group operations, advanced missile defense capabilities and seamless surface action group missions," he added in a statement.
The maneuver has been held regularly in the Baltic since 1972.