Germany and France will launch a program this month to develop a new marine patrol and surveillance aircraft, the German Navy said on Friday. The move, according to defense sources, is seen as a response to “a sharp increase in Russian submarine patrols,” Reuters said. German Defense Minister Ursula von der Leyen and her French counterpart, Florence Parly, plan to sign a letter of intent about the new “Maritime Airborne Warfare System” at the Berlin Air Show on April 27. Berlin and Paris agreed last July to seek a “European solution” to replace existing marine surveillance planes, and develop a road map to that end by mid-2018.