How many times did US President John F. Kennedy invoke executive privilege?

US President John F. Kennedy, invoked presidential or executive privilege only once during his tenure of the presidency. That was in February of 1962. At that time a US Senate committee, wanted to know the names of Secretary McNamara's subordinates that were deleting Defense Department reports and also removing " war like" passages from US generals and admirals. Kennedy relied that the names were not required and that Secretary McNamara took full responsibility for any deletions, and in so many Words meant " it won't happen again".Later Senator Stennis, agreed with Kennedy, however, Stennis did not concede any ground on future requests from Congress.

Basically, Stennis saw no need to have the names of the subordinates since the executive branch apologized. It became clear by his action, that the concession in no way precluded future requests that Congress might have concerning other issues.