fullstory Washington, Sept 3 (PTI) A top American intelligence official has said that the United States is a nation at war which is facing threat from al-Qaeda terrorists in Pakistan. "We are a nation at war. We are confronting a war in Afghanistan and a war in Iraq. We are confronting al-Qaeda and other terrorists in Pakistan," CIA Director Leon Panetta said at the Nationally Black Colleges and Universities Week Conference on Tuesday. Panetta said his agency's first responsibility is to protect the safety of the US. "We are confronting the challenge of nuclear proliferation in countries like North Korea and Iran... We are confronting a whole new challenge of something called cyber-security, which has the potential to in fact bring down our markets, bring down our power grid system, bring down our water systems and cripple this country," the CIA chief said.