Anti-American rioting spread yesterday to Tunisia, where police used tear gas to stop hundreds of protesters from storming the United States Embassy in protest over a film mocking the prophet Mohammed. The throngs of demonstrators, who carried the white and black banners of militant Salifist Muslims, had been protesting peacefully in Tunis for hours when about 300 started to break through the embassy gates. The embassy remained open as police forced the protesters back. Earlier, the US embassies in Tunisia and Algeria warned Americans to avoid crowded places because of expected protests. In Egypt, the powerful Muslim Brotherhood ensured that...