Dear Mr. DiBenedetto,
Thank you for posting your request on History Hub!
We searched the National Archives Catalog and located the Meeting Records and Memoranda, 1961 - 1963 in the Papers of John F. Kennedy: Presidential Papers: National Security Files, 1/20/1961 - 11/22/1963 (Collection JFK-4) that includes the file unit National Security Files: Meetings and Memoranda: National Security Action Memoranda, 2/3/1961 - 11/13/1963, which includes the digitize document National Security Action Memorandum No. 231 Middle Eastern Nuclear Capabilities. This document may be viewed online through the National Archives Catalog.
We also located the Country Files, 1/20/1961 - 11/22/1963 in Collection JFK-4 that may include files related to Israel. Plus, we located President Kennedy's Outgoing Executive Correspondence, 1/20/1961 - 11/22/1963 in the Papers of John F. Kennedy: Presidential Papers: White House Central Files: Chronological File, 1/20/1961 - 11/22/1963 (Collection JFK-6.3) that may include a copy of the letter you seek. These records are not available online. For more information about these records as well as for assistance identifying additional records that may be relevant, please contact the John F. Kennedy Library (LP-JFK) via email at firstname.lastname@example.org.
Further, we located Records Relating to Israel, 1/24/1957 - 11/1/1967 and Subject-Numeric Files, 2/1/1963 - 1973 in the General Records of the Department of State (Record Group 59). The later series of records is further described at Subject-Numeric Files, 1963-1973. Next, we located General Records, 1948 - 1961; Classified Central Subject Files, 1962 - 1968; and Ambassador's Subject Files, 1948 - 1975 of the U.S. Embassy, Israel, in the Records of the Foreign Service Posts of the Department of State (Record Group 84). Any one of the series may contain a copy of the letter you seek. For more information about these non-digitized records, please contact the National Archives at College Park - Textual Reference (RDT2) via email at Archives2reference@nara.gov.
Due to the COVID-19 pandemic and pursuant to guidance received from the Office of Management and Budget (OMB), NARA has adjusted its normal operations to balance the need of completing its mission-critical work while also adhering to the recommended social distancing for the safety of NARA staff. As a result of this re-prioritization of activities, you may experience a delay in receiving an initial acknowledgement as well as a substantive response to your reference request from LP-JFK and RDT2. We apologize for this inconvenience and appreciate your understanding and patience.
We hope this is helpful. Best of luck with your research!