Obama taps Brennan as CIA director NEW: John Brennan says his mission will be "to make sure that the CIA has the tools it needs" NEW: Obama: Brennan "is one of the hardest working public servants I have ever seen" Obama says he is nominating John Brennan to head the CIA Brennan, 57, has been Obama's chief counterterrorism adviser for four years Washington (CNN) -- President Barack Obama on Monday nominated his chief counterterrorism adviser to be the next CIA director. "In John Brennan, the men and women of the CIA will have the leadership of one of our nation's most skilled and respected intelligence professionals," Obama said at the White House. Brennan, 57, has been Obama's assistant for counterterrorism and homeland security since 2009. In that role, Obama said, Brennan worked closely with many government agencies. "Think about the results," Obama said. More al Qaeda leaders and commanders have been removed from the battlefield than at any time since 9/11. Obama announced Brennan's nomination at the same time he tapped former Sen. Chuck Hagel to become defense secretary. "John is legendary even in the White House for working hard," Obama said. He is one of the hardest working public servants I have ever seen. Brennan: Drone attacks are legal, ethical "If confirmed as director I will make it my mission to make sure that the CIA has the tools it needs to keep our nation safe and that its work always reflect the liberties, the freedoms and the values that we hold so dear," Brennan told reporters shortly after Obama tapped him for the job. After the 2008 election, Brennan was touted as a shoo-in for CIA director, but attacks from critics who claimed he supported the Bush administration's policy of harsh interrogations prompted him to drop out of consideration for the job. Returning to the CIA would be a homecoming of sorts for Brennan. Brennan joined the agency after responding to a newspaper want ad, and he spent 25 years there, developing a deep knowledge of the Mideast and fluency in Arabic. "He knows what the president wants from his intelligence community," said Bill Harlow, a former senior CIA official. And he also knows how to deliver it from having worked at the agency. ... There'll be no learning curve for him. But debate over the drone program and Brennan's position on CIA interrogations could make for some rough moments during his confirmation hearings. The fact he is coming from the West Wing and has frequently talked about the president's views on camera could make him political fodder, said Frances Fragos Townsend, CNN's national security contributor. "He's got to expect that (Capitol) Hill is going to treat him as a political person who is fair game now, rightly or wrongly," she said. At least one official outside Washington was singing Brennan's praises Monday. "None is more qualified, dedicated, or experienced," New York City Police Commissioner Raymond Kelly said in a statement. He understands fully that New York City remains in the crosshairs of terrorists overseas, and he is committed to undermining them there before they have an opportunity to strike here.