John Kennedy actually said...
On and after August 29, 1963, the proclamation of January 31, 1963 (identified in Part II B) of this proclamation) is terminated in part as specified in Part 11 (B) of this proclamation.
Context
Proclamation 3553—Proclamation of Protocol for the Accession of Spain to the General Agreement on Tariffs and Trade
09/05/1963