Six underwater minehunter drones will be sent to Ukraine from the UK, to help secure safe passage for vessels exporting food from the country.
The Royal Navy's Diving & Threat Exploitation Group and the US Navy 6th Fleet have already begun three-week courses at sea with Ukrainian personnel, teaching them to operate the Unmanned Underwater Vehicles (UUVs).
Designed for shallow coastal environments up to 100 metres deep, the drones' sensors can spot mines, like the ones left indiscriminately by Russia, for the Ukrainian Navy to destroy.
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Food exports have been under threat from early on in the war, with blockades between the Black Sea and Ukrainian ports preventing grain from leaving Ukraine.
A UN-brokered deal has since enabled some ships to leave, but efforts have been hampered by coastal Russian mines in what Defence Secretary Ben Wallace calls "cynical attempts to hold the world's food supply to ransom".
Three of the UUVs are being donated from Royal Navy stocks, while the other three have been purchased from industry partners.
Dozens of Ukrainians will be trained to use the underwater drones, while separate courses for sailors to operate Sandown Class Minehunter vessels have already taken place.
During the three weeks, personnel are taught to interpret the data sent back by the lightweight UUVs to identify mock mines.
Captain Ben Vickery, Captain of Royal Navy Diving and Mine Warfare, said: "The Ukrainian personnel have been fantastic, and it is a pleasure to be working with them and helping them in their struggle to defend their homeland against the aggression they are currently suffering.
"These incredible, motivated and very professional sailors have thrown themselves into the task and have made incredible progress gaining an excellent level of proficiency."
Admiral Sir Ben Key, First Sea Lord and Chief of the Naval Staff, said: "Through the expert skills being taught here, our Ukrainian allies will be able to clear their own waters of mines.
"These weapons target shipping indiscriminately, but particularly affect civilian traffic and trade, and have had a devastating impact on freedom of navigation in the Black Sea.
"This training is another powerful demonstration of the UK's ongoing commitment to Ukraine in their fight to defend their country and repel Russian aggression."