On June 20th 1941 U203 sighted the a battleship escorted by a single destroyer. This BB was the USS Texas, part of a temporary US naval task force which also included the BB's New York & Arkansas, which had been deployed to help the British intercept a anticipated sortie by the Lutzow.
The Texas was 800 miles south west of Iceland and 10miles inside a zone in which Hitler had authrorised attacks on Neutral warships.
U203 went to battlestations and for the next 16 hours he pursued his quarry, but the Texas was going at high-speed. Within that 16hr chase they had gone some 148miles into that zone. Later that day U203's commander reported his actions. This caused a great stir with Barborossa only being some 2 days away.
So What If U203 had attacked and sank the Texas within the zone, would it have been enough to tip the US into the war with Britain against Germany, and with Germany about to undertake Barbarossa?
And before anybody turns this into an opportunity to lecture about real history, yes we all know about the undeclared naval war and plenty of unnatural, pro-British actions of the U.S. by then. So one can make a semantic argument the U.S .was at "war" already.
The key question is, if the U203 struck and sank the USS Texas, would this have led the US to do a full scale war with Germany, involving "the works", a declaration of war and raising of forces for bombings and invasions in the European Theater of Operations?
The alternatives to this being a simple continuation of the status quo or escalated naval war, or lastly...
an investigation of US actions and a reining in of FDR's pro-Allied naval policy.
What's your answer and why do you think so?