nations. The USSR supported Syrian attacks and blamed the violent acts on Israel. Syria did not hesitate to act because it believed that the other Arab states would support it and Israel was not capable of defeating it. In the UAR, the USSR motivated Nasser to have the UN forces leave the Sinai Peninsula and the Gaza Strip and to blockade the Straits of Tiran. Like Nasser, the USSR didn't believe that Israel would start a war on its own. Even if Israel did attack, it was unlikely that Israel would be capable of defeating the Arab states. Syria believed that, with the help of the UAR, it could beat Israel. On May 11, the USSR warned the UAR that Israel troops were gathering on the border with Syria and that an invasion was planned for May 18 to May 22. At this time, the USSR also began to publish accusations against Israel in order to cement the defensive unity of the UAR and Syria. Syria after 1966 Since 1966, Syria had obtained most of its military equipment from the Soviet Union. In 1971, when Syrian Air Force Commander Hafez al-Assad became President of Syria by way of a coup, he elected to maintain a strategic policy of close cooperation with the Soviet Union. The same year, Assad agreed to allow Soviet military personnel to keep a naval base in Tartus. In February 1972, Syria signed a peace and security pact with the Soviet Union as a means to strengthen its defense capability. During the year, Moscow delivered more than $135 million in Soviet arms to Damascus. In 1980, Syria signed a Treaty of Friendship and Cooperation with the Soviet Union. A secret protocol to the treaty reputedly detailed Soviet military obligations to Syria and gave the USSR to power to mandate the dispatch of Soviet troops to Syria in case of an Israeli invasion. Syrian defense minister Mustafa Tlass warned in 1984 that the Soviet Union would dispatch two Soviet airborne divisions to Syria within eight hours in the event of a conflict with Israel. Tlas's has also stated that the Soviet Union would use nuclear weapons to protect Syria. Tlas's statements, however, were not endorsed by the Soviet Union. Syrian–Soviet nuclear cooperation was limited to a February 1983 agreement for cooperation and exchange for peaceful purposes. In addition to the PLO, Syria and Iraq, the Soviet Union also