Production of the Messerschmitt Me 262A fighter versions continued, as well as the development of advanced piston-engined fighters such as the Dornier Do 335 as per Hitler's personal request on May 23, 1944, before the July 3 announcement of the program. Bomber designs powered by piston engines were severely curtailed or outright cancelled, with only jet bombers allowed to continue in production, such as the Arado Ar 234. New jet bombers such as the Junkers Ju 287 and Heinkel He 343 were worked on fitfully as low priority projects in the last months of the war.