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. Zuckerberg said that artificial intelligence represents the best solution to misinformation on Facebook, but won't be ready for another five to ten years. In the run-up to the 2016 election, Russian intelligence operatives used Facebook and other online platforms to spread divisive content generally aimed at boosting President Donald Trump's electoral chances. On Tuesday, a remorseful Zuckerberg admitted that his company's response was slow, calling it one of his "greatest regrets." Zuckerberg argued that the highly sophisticated Russian approach to spreading its influence online has left his company at a distinct disadvantage.