US President Donald Trump signed an executive order on Monday calling the antifa movement a "terrorist organization," the White House said, after promising actions targeting left-wing groups following Charlie Kirk's assassination. Kirk, a prominent conservative activist with close ties to Trump, was assassinated on September 10 while speaking on a college campus in Utah. A 22-year-old technical college student has been charged with Kirk's murder. Investigators are still looking for a motive and have not said the suspect operated in concert with any groups. But the Trump administration has used the killing as a pretext to revive years-old plans to target left-wing groups they regard as being hostile to conservative views. Antifa, short for anti-fascist, is a "decentralised, leaderless movement...