ocean against Japan.However after the war started
the Atlantic Fleet deployed subs to look for U-Boats.
That were crossing the atlantic to the east coast. They're were encounters between them .
The US subs were S or R class subs of WW1 era.
Also in Fall 1942 a squadron of 6 Gato class subs assigned to the 50th sub squadron were sent to England and under British control patrolled off France,Norway and Spain looking for Blockade runners,also convoys that came from Norway and Spain until Winter,1943. One of them attacked a German convoy and sank a freighter and escaped four 4 german destroyers. The subs sent were Barb SS-220,Blackfish SS-221,Shad SS-235,Herring SS-233,Gunnel SS- 253, and Gurnard SS-254.
While Spain was a neutral country during the war.
It was a friend to Germany the same way America was to England yet while being neutral.
I think this has diorama potential. US sub looking at the Tirpitz in a fjord or German destroyer depth charging a US sub or U-boat vs.
Gato sub .HTH.