In mid May 1967, the Soviet Union issued warnings to Nasser of an impending Israeli attack on Syria. Although the chief of staff Mohamed Fawzi verified them as "baseless", Nasser took three successive steps that made the war virtually inevitable: On 14 May he deployed his troops in Sinai near the border with Israel, on 19 May he expelled the UN peacekeepers stationed in the Sinai Peninsula border with Israel, and on 23 May he closed the Straits of Tiran to Israeli shipping. On 26 May Nasser declared, "The battle will be a general one and our basic objective will be to destroy Israel".

Who warned of impending Israeli attack on Syria in May 1967?