Z s.e.a.l.s as well. here s what we saw. on high alert in the black sea, u.s. navy s.e.a.l.s, romanian and british special forces practice raid ing an enemy ship, an exercise that requires a lot of skill, but also strong cooperation, a member of the romanian special forces tells me. the helicopter session, the synchronization is very important so all the teams can get on board in the ship in the exact time they should. reporter: these are among nato s most elite unit and they allowed us to film on the condition we would not reveal their identities. the raid involves both fast, rigid inflatable boats as well as a chopper to land troops on the ship, search it and detain would be enemy combatants. this drill is part of a much larger special forces exercise called trojan footprint involving some 30 countries, both nato and non-nato allies. on the face of it, this exercise