Germany's defence ministry hasdecided to buy high-altitude MQ-4C Triton unmanned surveillance planes built by U.S. weapons maker Northrop Grumman Corp for deliveries after 2025, ministry sources said Tuesday.The new drones will replace the Euro Hawk program, which Berlin cancelled in May 2013 after it became clear that it could cost up to 600 million euros to get the system approved for use in civil airspace. The plan, which must still be approved by parliament, calls for Germany to buy the new aircraft from the U.S. Navy, which awarded Northrop a contract to design the unmanned aircraft in April 2008. Sensors for the new aircraft are to be built by Airbus, as planned under the previous program, thesources said.It was not immediately clear how many planes the ministry would buy, or at what cost. Under the cancelled program, it had planned to buy five Euro Hawk aircraft for 1.2 billion euros. Then-Defence Minister Thomas de Maiziere came under pressure after he was forced to cancel the previous Euro Hawk program in 2013 after it became clear it would cost hundreds of millions of euros to win aviation approval for the aircraft.