WASHINGTON, Nov 14 (Reuters) - Demonstrators began to gather in Washington on Tuesday for a "March for Israel" that organizers say will show solidarity with Israel in its war with Hamas and condemn rising antisemitism. Streets were closed around much of downtown amid heightened security, as several thousand people gathered in late morning bright sunshine on the National Mall, many draped in Israeli and American flags. loading The website for the march, organized by Jewish Federations of North America and Conference of Presidents of Major American Jewish Organizations, said communities from across the U.S. would gather "to demonstrate our commitment...