Computer attacks against U.S. infrastructure are on the rise, the head of the National Security Agency said. Gen. Keith B. Alexander, who also directs the U.S. Cyber Command, spoke Thursday at the Aspen Security Forum in Colorado. He said online attacks that could destroy computer systems have increased 17-fold since 2009, The New York Times reported. Alexander was critical Thursday of the nation\'s ability to handle a serious cyberattack on critical U.S. infrastructure, telling moderator Pete Williams of NBC he would give the United States a three on a scale of one to 10. \"I\'m worried most about the power. I\'m worried about water, I think those are the ones that need the most help,\" Alexander said. Alexander is pushing Congress to pass the Cybersecurity Act of 2012, CNN said. The bill, currently moving through the Senate, would allow the private sector to better assist in protecting the nation\'s water, electric, banking, transportation and other areas of infrastructure, supporters say.