Question: When was the last time a us submarine sunk?
Disambiguated questions and answers: question: When was the last time a us nuclear submarine sunk?
When was the last time a decommissioned us submarine sunk?
When was the last time a us submarine sunk prior to commissioning?
When was the last time a us non-nuclear submarine sunk?
answer: May 22, 1968
1 June 1971
15 May 1969
18:57 on 29 May 1958
29 May 1958
Natural Questions answer: 21 February 1946 (from the Wikipedia article "List of lost United States submarines")