The "terms of neutrality" certainly do NOT dictate who we may and may not trade with. The terms of sovreignty certainly DO dictate just that. The choice is ours, not ze Germans.
I suggest remaining silent and thought a fool rather than posting and removing all doubt...Contraband(munitions for making war), were being sent to the British which violated international laws of neutrality, and by the 1856 Declaration of Paris, made vessels shipping contraband subject to search and seizure and capture. Shipping munitions on passenger vessels put the Germans in a tough spot.
The blockcade of Germany was 'illegal' under The Declaration of London, because it blocked food stuffs from neutrals, however, all the signatories of the DoL had not signed so it was not law per say.