Other navies wanted Italy's circling-torpedo technology

Did only Germany and Italy develop looping torpedoes?

Other countries were working on them, and the Italian system attracted interest because its performance had proved difficult to reproduce.

Other countries were developing looping torpedoes even though Germany and Italy had fielded designs. Germany is said to have regarded the Italian weapon as better than its own. In this account, obtaining Italian torpedo technology was a major Allied priority in 1943. The attraction was a working solution to a problem that had resisted considerable effort and expenditure.