CHICAGO — President-elect Barack Obama this morning announced Robert Gates would remain as defense secretary, making President Bush's Pentagon chief his own as he seeks to wind down the U.S. role in Iraq.

Obama picked former campaign rival Hillary Rodham Clinton as secretary of state.

At a news conference, Obama also introduced retired Marine Gen. James Jones as White House national security adviser, former Justice Department official Eric Holder as attorney general and Arizona Gov. Janet Napolitano as secretary of homeland security.

He also appointed campaign foreign policy aide Susan Rice as his ambassador to the United Nations. Obama said he would make her a member of the Cabinet, an increase in stature from the Bush era.

The announcements rounded out the top tier of the team that will advise the incoming chief executive on foreign and national security issues in an era marked by wars in Iraq and Afghanistan and terrorism around the globe.

"The time has come for a new beginning, a new dawn of American leadership to overcome the challenges of the 21st century," Obama said as his Cabinet picks stood behind him on a flag-draped stage.

Gates' presence in Chicago made him a visible symbol of the transition in power from the Bush administration to one headed by Obama.

By The Associated Press