NATO will lead the world’s largest submarine rescue exercise in the Baltic sea without Russian involvement after the alliance suspended cooperation with Moscow following its annexation of Crimea.

Ships, submarines, aircraft from 18 NATO and non-alliance states will conduct the operation off the coast of Gdynia, Poland.

The rescue exercise, dubbed Dynamic Monarch 2014, runs every three years and will be staged from May 12-23.

During the drill the three participating submarines will take turns settling on the bottom of the ocean to allow the NATO Submarine Rescue System (NSRS) to mate to its rescue hatch and test submarine rescue procedures.

The equipment, explained NATO’s Commander of Submarines Rear Admiral Robert Kamensky, was designed to work with all submarines that meet international standards and become disabled at a recoverable depth.

“These are complex systems operating in an unforgiving environment where there is no room for errors,” said Rear Admiral Kamensky. “This is why we need to train together to ensure our operators are at their very best.”