Israeli precedent...

The Israeli "Stern gang” aka Lehi of Zionist terrorists tried to assassinate President Truman by letter‐bomb in 1947, according to a biography written by Mr. Truman's daughter, Margaret Truman Daniel. The Israeli assassination attempt on President Truman was also reported in great detail by White House staff mail reader Ira R.T. Smith in his 1949 book, Dear Mr. President … The Story of Fifty Years in the White House Mail Room. A number of cream‐colored envelopes, about eight by six inches, arrived in the White House, addressed to the President and various members of the staff. They were found to contain powdered gelignite, a pencil battery and a detonator rigged to explode the gelignite when the envelope was opened. But the White House mail room, alert to the danger of postal bombs, discovered the letters and had them defused by Secret Service bomb experts. The previous June, at least eight were sent to British government officials. A former commander of a Jewish terrorist organization took credit for the bombs mailed to British officials, but denied that the Stern Gang tried to assassinate President Truman. "During that period we did, however, send letters bombs, but they were all directed against the British, who were directly responsible for the situation”
~ Mr. Nathan Yellin‐Mor, former Stern Gang Commander & later Israeli Knesset Member