In a news conference in Chicago, Obama introduced Sen. Hillary Rodham Clinton as Secretary of State, America’s top diplomat who will be the face of Obama’s efforts to remake the country’s foreign policy. Obama also announced that Bush’s Defense Secretary, Robert M. Gates, has agreed to remain in the job in the new administration, providing continuity while taking on what the president-elect said would be a new mission: “responsibly ending the war in Iraq through a successful transition to Iraqi control.”

“I assembled this team because I’m a strong believer in strong personalities and strong opinions. I think that’s how the best decisions are made,” Obama said. He vowed to counter the danger of “group-think” that precludes dissenting views and pledged to welcome “a vigorous debate inside the White House.”

He stressed, however, that he will set policy, will be responsible for his administration’s “vision” and will expect his team to implement decisions once they are made. “So, as Harry Truman said, the buck will stop with me.”

As he introduced Clinton, Gates and other members of his team, Obama said that “in the 21st century, our destiny is shared with the world’s” and that the US has a stake in global events regarding such matters as financial markets, public health, climate change and security from terrorism. “In this uncertain world, the time has come for a new beginning — a new dawn of American leadership to overcome the challenges of the 21st century,” he said. “We will strengthen our capacity to defeat our enemies and support our friends. We will renew old alliances and forge new and enduring partnerships. We will show the world once more that America is relentless in defense of our people, steady in advancing our interests, and committed to the ideals that shine as a beacon to the world: democracy and justice; opportunity and unyielding hope — because American values are America’s greatest export to the world.”

Obama introduced retired Marine Gen. James L. Jones as his National Security Adviser. Jones, operating inside the White House, will be charged with melding military and diplomatic policy and with helping Obama navigate the two bureaucracies. The three other Cabinet selections announced Monday were Eric H. Holder Jr. as Attorney General, Arizona Gov. Janet Napolitano as Secretary of Homeland Security and Susan Rice as US Ambassador to the United Nations.

“I am confident that this team is what we need to make a new beginning for American national security,” Obama said after introducing each member. “And as we move forward, with respect for America’s tradition of a bipartisan national security policy and a commitment to national unity, we have to recall that when it comes to keeping our nation and our people safe, we are not Republicans or Democrats, we are Americans.” The trio of Clinton, Gates and Jones represents a centrist team that has angered some of Obama’s most ardent liberal supporters, who had expected a foreign policy team with left-leaning credentials.

But as he did in choosing his economic team, Obama favoured experience over ideology in forming his national security cabinet.