1969 Letter-bomb era inspected mail to Israeli President; postmark date error

1969 Letter-bomb era inspected mail to Israeli President; postmark date error
Letter-bomb era inspected mail: 11 NOV 1969 airmail stationary cover from CHICAGO to President Zalman Shazar JERUSALEM, franked 25c per postage period rate & tied by local machine cancel; backstamped 16-11-69 JERUSALEM arrival using Cancer Awareness machine slogan cancel: following 1967 6-Day War, there was a greater threat of mail bombs sent to Jewish/Israeli targets: here this cover marked by triangular "NIVDAK" (inspected) handstamp + "President's House" 1-line text cachet - rare combination as this type of marked postal stationary was routinely destroyed. Slit open at top.