Anti-Israel student activists unleashed mayhem at Columbia University on Tuesday afternoon, which marked the beginning of the spring semester. Several keffiyeh-clad student activists stormed an Israeli history class and passed out anti-Semitic flyers glorifying Hamas, depicting the Star of David being crushed, and promising violence. Others vandalized the campus and called on their followers to shut down the university. Four student activists, donning keffiyehs, marched into the class, "History