Using U.S. archival documents as well as insights gained from Israeli historians who made excellent use of Soviet sources, this article examines the diplomacy and military developments that occurred late in the Egyptian-Israeli War of Attrition. Understanding that Moscow was pursuing a more forward policy than Washington officials understood at the time, it becomes clear that Soviet military intervention began earlier than American and Israeli decision-makers then recognized or than historians have understood until recently. Likewise, the operational deployment of Russian air defense forces and fighter pilots challenged Israeli air superiority in the skies over the Suez Canal, which separated Egyptian and Israeli troops. While American diplomats were willing to help the Israelis with equipment and countermeasures to deal with the new threat, they put enormous pressure on Jerusalem not only to accept the ceasefire that ended the conflict but also to not respond militarily to Egyptian violations of the agreement. Thus, Israel found itself in a fundamentally more vulnerable position when the shooting stopped in August 1970.