WASHINGTON - OCTOBER 07:  Bob Grenier, former CIA station chief in Islamabad, testifies before the Senate Foreign Relations Committee during a hearing about Al-Qaeda and Afghanistan on Capitol Hill October 7, 2009 in Washington, DC. On the eighth anniversary of the United States' invasion of Afghanistan, witnesses testified, and disagreed, about what affect a withdrawal of U.S. forces from that country would have on Al-Qaeda. Getty Images logo Getty Images 1 month ago

WASHINGTON - OCTOBER 07: Bob Grenier, former CIA station chief in Islamabad, testifies before the Senate Foreign Relations Committee during a hearing about Al-Qaeda and Afghanistan on Capitol Hill October 7, 2009 in Washington, DC. On the eighth anniversary of the United States' invasion of Afghanistan, witnesses testified, and disagreed, about what affect a withdrawal of U.S. forces from that country would have on Al-Qaeda.