Various proposals were put forward, but these plans were all eventually abandoned as they were too expensive, too reliant on rapidly diminishing materiel and production capacity, and/or technically infeasible.

[2] On 8 July 1938, barely two years after the death of Germany's main strategic bombing advocate, Generalleutnant Walter Wever, and eight months after the Reich Air Ministry awarded the contract for the design of the Heinkel He 177, Germany's only operational heavy bomber during the war years, the Luftwaffe's commander-in-chief Hermann Göring gave a speech saying, "I completely lack the bombers capable of round-trip flights to New York with a 4.5-tonne bomb load.

"[3] Canadian historian Holger H. Herwig claims the plan started as a result of discussions by Hitler in November 1940 and May 1941 when he stated his need to "deploy long-range bombers against American cities from the Azores."

Due to their location, he thought the Portuguese Azores islands were Germany's "only possibility of carrying out aerial attacks from a land base against the United States.

According to military historian James P. Duffy, Hitler "saw in the Azores the ... possibility for carrying out aerial attacks from a land base against the United States ... [which in turn would] force it to build up a large antiaircraft defense.

"[3] The anticipated result would have been to force the United States to use more of its antiaircraft capabilities—guns and fighter planes—for its own defense rather than for that of Great Britain, thereby allowing the Luftwaffe to attack the latter country with less resistance.

As both the Me 264 and He 277 were each intended to be four-engined bombers from their origins, the troubling situation of being unable to develop combat-reliable piston aviation engines of 1,500 kW (2,000 PS) and above output levels led to both designs being considered for six-engined upgrades, with Messerschmitt's paper project for a 47.5 meter wingspan "Me 264B" airframe upgrade to use six BMW 801E radials,[10] and the Heinkel firm's July 23, 1943-dated request from the RLM to propose a 45-meter wingspan, six-engined variant of the still-unfinalized He 277 airframe design that could alternatively accommodate four of the troublesome, over-1,500 kW output apiece Junkers Jumo 222 24-cylinder six-bank liquid-cooled engines, or two additional BMW 801E radials beyond the four it was originally meant to use.

[12] One idea similar to Mistel-Gespann was to have a Heinkel He 177 bomber carry a Dornier Do 217, powered with an additional Lorin-Staustrahltriebwerk (Lorin-ramjet), as far as possible over the Atlantic before releasing it.

Air Staff General Kreipe wrote in his diary that the German navy could not supply a U-boat off the United States to pick up the aircrew.

[3] Were New York City to be bombed, the required combat radius was 11,680 kilometres (7,260 mi), as the bomber would have needed to make a return trip without refueling.

Nazi Germany's nuclear programme was years behind the Allies, and did not include weapons in the form of aerial bombs, so it was unlikely that the Amerikabomber could have made a major difference to the outcome of the war.