Underlining this bit of nonsense about the Germans using submarine-towed V-2 launchers to attack the United States during World War II is the implicit assumption that the US is fundamentally unlike other countries, and that piercing US immunity to attack is somehow catastrophic to the American way of life. While in some sense admirable on aspirational grounds, this assumption comes with its own dangerous set of policy implications. To be clear, this is what would have happened if the Germans had managed to tow a dozen V-2 rocket canisters within range of New York City:
1. The submarine towing the canisters would very likely have been sighted on its way to its launching area, and destroyed by Allied aircraft and surface vessels. Towed missile canisters do not, by and large, enhance the stealth characteristics of a submarine.
2. Some percentage of the untested canisters would have failed upon deployment.
3. Optimistically, we’ll say that ten V-2s of the notional twelve would have launched successfully. V-2s had gyroscopic guidance systems, which means that the launcher needs to know where he is in relation to the target in order to pre-set coordinates and flight path. As adjusting the submerged V-2s would likely have been impossible, this means that the submarine would have to surface at a point pre-determined with precision. This is unlikely. Alternatively, it’s possible that the Germans could have installed some kind of guide beam equipment on the submarine, which would enhance accuracy but force the submarine to surface under extremely dangerous conditions.
4. The V-2 had a CEP (circular error probability) of 4.5 km, meaning that half of the missiles would strike within 4.5 km of the target. In the exceedingly unlikely event that the missile-towing U-boat survived to launch from its predetermined point within 200ish miles of Manhattan, half of the launched missiles would fall within 4.5km of, say, the Empire State Building.
5. The V-2 carried a 2000# warhead, which could have done significant damage to any target that it hit. In practice, V-2s launched by the Germans in World War II ended up killing roughly 2.3 people per missile. If the Germans got lucky, however, they might kill a lot more; the two most deadly strikes during WWII killed 550 and 160 people, respectively.
In the end, the Germans could have killed some Americans at huge risk and at huge expense. A standard Type VII boat using its 88mm deck gun could probably have done as well if the Germans had ever thought it useful to risk a submarine in order to kill a few Americans unlucky enough to have the wrong beachfront property. Now, it sucks when Americans get killed, but the actual operation would have had NO EFFECT WHATSOEVER on the US war effort.
This last point is really key; suffering from actual bombardment (London was hit by some 1350 V-2s) tends to lend some perspective as to the actual effect of weapons of war. This is NOT to say that the United States would have benefited from suffering from German attacks; rather, it’s to suggest that US political culture has been afflicted with an unhealthy addiction to immunity which causes wild overreactions to real and perceived threats. An actual German effort to carry out this proposed operation would have been exceedingly expensive and almost certainly suicidal; even Hitler noted that V-2s were like artillery shells, only much more expensive. Similarly, implausible scenarios about North Korean ballistic missile attacks and Scuds launched from barges in the Atlantic almost never make sense in the details; they’re only compelling in the context of the threat they pose to the American sense of immunity, rather than the threat that they pose to the American population, economy, military establishment, etc.