A system and method is provided to replenish a submarine's tactical capabilities, e.g., weapons, sensors and communications, while the submarine remains within a hostile environment. One or more Underwater Combat Vehicles (UCV's) are pre-positioned at strategic locations or are launched from a surface and/or airborne platform. The UCV's include full tactical capabilities, which can attach to and be integrated with a submarine's capabilities. To initiate replenishment, a submarine broadcasts a signal, or dispatches one of the UCV's under its direct control, to make contact with one of the pre-positioned UCV's or with a central command platform. The pre-positioned UCV's are programmed to search for and locate the submarine. This can either be accomplished using signals broadcast from the submarine, or using UCV internal navigation systems and a last known position for the submarine. Once located, communication between the submarine and UCV allows docking of the UCV onto the submarine.