WASHINGTON/CAIRO, May 10 (Reuters) - Relative calm prevailed around the Strait of Hormuz early on Sunday after days of sporadic flare-ups, as the United States waited for Iran's response to its latest... By Idrees Ali, Erin Banco and Hatem Maher WASHINGTON/CAIRO, May 10 (Reuters) - Relative calm prevailed around the Strait of Hormuz early on Sunday after days of sporadic flare-ups, as the United States waited for Iran's response to its latest proposa... [4249 chars]