BAGHDAD (Reuters) - Iraqi forces breached on Tuesday the city limits of Tal Afar, an Islamic State stronghold west of Mosul, military authorities said. Army and counter terrorism units broke into the city from the eastern and southern sides, according to statements from the Iraqi joint operations command.  Security forces launched an offensive to take back the city on Sunday, their latest objective in a U.S.-backed campaign to defeat the Sunni Muslim jihadists, who remain in control of territory in western Iraq and eastern Syria.  