Good grief. From Ha'aretz:
For some time, the United States had had an emergency plan to attack Israel, a plan updated just prior to the 1967 war, aimed at preventing Israel from expanding westward, into Sinai, or eastward, into the West Bank.In May 1967, one of the U.S. commands was charged with the task of removing the plan from the safe, refreshing it and preparing for an order to go into action. This unknown aspect of the war was revealed in what was originally a top-secret study conducted by the Institute for Defense Analyses in Washington. The full story is detailed in Haaretz' Independence Day Supplement.