Facing hours of sharp questioning in Congress over his company’s privacy practices and its response to Russian election meddling, Facebook founder Mark Zuckerberg repeatedly argued on Tuesday that his company is engaged in an “arms race” with Moscow’s intelligence agencies. On Tuesday, a remorseful Zuckerberg admitted that his company’s response was slow, calling it one of his “greatest regrets.”  Zuckerberg said his company’s efforts to ban terrorist content from the platform gives the company hope that it can use artificial intelligence to detect and block calls to violence. Some 99 percent of al Qaeda and Islamic State content is blocked before anyone has a chance to see it, Zuckerberg claimed. “We hope to develop more tools like this.” (The Counter Extremism Project, a nonprofit group, argues these figures are overstated and that prominent Islamist extremists remain active on the platform.)”