On 27 September 1955, Egyptian president Gamal Abdel Nasser announced an agreement to have Egypt purchase some $320 million worth of Soviet-built weapons from Czechoslovakia. Payment on an interest-free basis would be spaced out over 12 years in shipments of Egyptian cotton. In addition to the weapons, Czech and Soviet instructors would be sent to Egypt. In a parallel treaty, Syria purchased from Soviet bloc countries tanks, MiG jet fighters, artillery pieces, and armored vehicles. The implications of the arms sale were great. Among other things, it emboldened Nasser to continue his hostile behavior toward Israel (including sponsoring and giving safe haven to Palestinian fedayeen groups operating against Israel from bases in the Egyptian-held Gaza Strip and taking steps to remilitarize parts of the Sinai Peninsula in violation of the 1949 armistice agreement with Israel). These actions in turn caused a heightened sense among Israel's leadership about the long-term security threat posed by Egypt and the need to preempt this threat, thereby accelerating the slide toward war in the fall of 1956.
Historical Dictionary of Israel. Bernard Reich David H. Goldberg. Edited by Jon Woronoff..