A new dawn of American leadership has arrived, says Obama

President-elect unveils his security team with Clinton as Secretary of State

Barack Obama called for a "a new dawn of American leadership" yesterday as he formally introduced his once bitter rival for the presidency, Hillary Clinton, as his choice for Secretary of State.

"We will strengthen our capacity to defeat our enemies and support our friends," the President-elect said at a news conference in Chicago that was long on platitudes and short on specifics. "We will renew old alliances and forge new and enduring partnerships."

"Hillary's appointment is a sign to friend and foe of the seriousness of my commitment to renew American diplomacy and restore our alliances," Mr Obama added, in a pointed reference to George Bush's Iraq legacy and the damage to America's US standing in the world.

With a Stars and Stripes flag flying behind her, Mrs Clinton smiled and listened intently as Mr Obama introduced her as "a friend, a colleague, a source of counsel and as a campaign opponent" who "possesses an extraordinary intelligence and toughness and a remarkable work ethic".

"Mr President-elect, thank you for this honour," she responded. "If confirmed, I will give this assignment, your administration and our country my all." She added that it would be "a difficult and exciting adventure", coming at a time when two wars were raging, the world economy was reeling, the climate warming and terrorists continuing to launch attacks.

Mr Obama also confirmed that Robert Gates would stay on as Defence Secretary, a well-telegraphed gesture to Republicans at a time when he is drawing up plans to end US involvement in Iraq within 16 months of taking office. He has appointed the much-decorated marine, General James Jones, as his National Security Adviser. Susan Rice, his foreign policy adviser on the campaign trail, will be given cabinet rank as the next UN ambassador. The Arizona Governor, Janet Napolitano, is the new Homeland Security chief and Eric Holder, a veteran of Bill Clinton's administration, will be the country's new Attorney General.

In yet another dig at the Bush regime's efforts to skirt around the US constitution, especially when dealing with terror suspects, Mr Obama said: "Let me be clear: the Attorney General serves the American people and I have every expectation that Eric will protect our people, uphold the public trust and adhere to our constitution." Mr Obama's national security team includes military Cold War veterans and diplomatic pragmatists. But by nominating Mrs Clinton as his Secretary of State, he has added a political heavyweight to his team. She is already on first-name terms with many world leaders and shares his vision of an America that is admired rather than feared in the world. Signalling that, for now at least, Mrs Clinton will be first among equals in his foreign policy team, the President-elect draped his arm over her shoulder as they left the press conference, with the rest of his new team straggling behind.

Mrs Clinton declared that the crises around the world were such that America could not solve them alone and that the rest of the world could not solve them without the US. Americans were demanding that their country's standing in the world improved, she said in a nod to her new boss. To her supporters, as much as to the media, she said "the best way to continue serving my country" was to join the Obama administration "at this defining moment". Quoting President John F Kennedy, she said: "I am proud to join you on what will be a difficult and exciting adventure in this new century."

Mr Obama pointed to potential fireworks ahead, saying that in choosing independent-minded Mrs Clinton and Mr Gates, he wanted people with strong opinions around him. "I am a strong believer in strong personalities and strong opinions," he said, adding that staff in the White House could "get wrapped up in group-think".

He would welcome vigorous debate, he said, but warned: "I will be setting policy as President. The buck will stop with me."

Mrs Clinton's diplomatic skills will soon be tested on everything from Iran and North Korea's nuclear proliferation, to climate change negotiations and re-energising the Middle East peace talks. Another of Mr Obama's priorities may be sending Mrs Clinton to Sudan to signal that the US will not stand idly by while mass atrocities are committed by the government of President Omar al-Bashir.