Army Navy Air Force (PLANAF) to replace the H-6G; has greater payload and range with performance similar to H-6K. Xian H-6M – (Cruise Missile Carrier) Fitted with terrain-following system and four under-wing hardpoints for weapons carriage. No internal bomb bay or defensive armament. Production of this variant is believed to have resumed in early 2006. Xian H-6N – (Nuclear Bomber) Reshaped fuselage in place of the bomb bay to mount an air-launched ballistic missile, likely the CH-AS-X-13 - a variant of the DF-21 anti-ship ballistic missile. It may also carry the CJ-10K/KD-20 or KD-63 land attack cruise missiles. The bomber may have entered service in 2018. Xian HD-6 – (Electronic Warfare Aircraft) Solid nose and canoe fairing believed to contain electronic counter-measures equipment. Aerial refueling variants Xian HY-6 – (Air Refueler) First successful in-flight refuelling tanker variant in Chinese service. Retained PV-23 fire control system of H-6 and thus can still be deployed as a missile launcher. Xian HY-6U – (Air Refueler) Modified HY-6 tanker in service with the PLAAF, with PV-23 fire control system and Type 244 radar deleted, and thus a dedicated refueling aircraft Also referred as H-6U Xian HY-6D – (Naval Air Refueler) First aerial refueling tanker for PLANAF, converted from H-6D. The most distinct difference between HY-6U and HY-6D is that HY-6U has a metal nose cone, while HY-6D still has the transparent glass nose. Like the original HY-6, PV-23 fire control system is also retained on HY-6D, which enables the aircraft also to serve as a missile carrying and launching platform. Xian HY-6DU – (Naval Air Refueler) Aerial refuelling tanker for the PLANAF, modified HY-6D, also referred as H-6DU. Similar to HY-6U, HY-6DU is a dedicated aerial refueling tanker when its PV-23 fire control system is removed from the aircraft. Export variants Xian B-6D – (Maritime Strike Bomber) Export version of the H-6D. Testbeds, prototypes and proposed variants Xian H-6I – Modified version powered by four Rolls-Royce Spey Mk 512 turbofan engines, originally purchased as spare engines for Hawker Siddeley Tridents in service with CAAC. Modifications included a lengthened fuselage and smaller engine nacelles with smaller air intakes in the wing roots, where the original two turbojet engines were replaced with two Spey turbofans. Two more Spey engines mounted on pylons, one under each wing, outboard of the undercarriage sponsons. Ferry range increased to 8,100 km (with standard payload), and combat radius increased to over