Fresh from his historic triumph, US president-elect Barack Obama promised the outside world "a new dawn of American leadership" that analysts say faces daunting challenges.

In a victory speech from Chicago that promised a sharp change from the past eight years, Obama acknowledged the sobering realities before him when he offered support to those who seek peace and a warning to potential enemies.

"Our stories are singular, but our destiny is shared, and a new dawn of American leadership is at hand," the son of a Kenyan father and a white American mother said, reaching beyond his supporters there to people worldwide.

"To those who would tear the world down: We will defeat you. To those who seek peace and security: We support you," said the 47-year-old Democrat.

Obama, a Harvard-trained lawyer, said the United States proved anew that its strength flows not from its weapons or wealth but from its ideals of "democracy, liberty, opportunity and unyielding hope."

Celebrations from London to Kenya

As throughout the campaign, Obama's ability to strike a chord beyond US shores proved strong as supporters erupted into song and dance from the bars of London and Sydney to a sleepy village in Kenya.

He raised hopes among Palestinians and Israelis who look to the United States to help settle their decades-old conflict as well as among those in Tehran and Havana that seek an end to adversarial ties with Washington.

But analysts tamp down the hopes from the man elected America's first black president as he prepares to take office on 20 January and wrestle with ending the wars and confrontations that erupted under his predecessor George W. Bush.

Obama, they say, will try to extricate US troops from Iraq, deal with a troublesome Iran, tackle the threat of "catastrophic" terrorism, and defeat a worsening insurgency straddling Afghanistan and a nuclear-armed Pakistan.

Also high on his list are resolving the global economic crisis, pursuing North Korea's nuclear disarmament, preserving the Middle East peace process, curbing global warming, and checking a "resurgent" Russia.

What are Obama's three goals?

Obama's website highlights three goals: "Secure loose nuclear materials from terrorists"; "pursue tough, direct diplomacy without preconditions to end the threat from Iran;" and "renew American diplomacy".

Obama, analysts say, also instinctively wants to reach out to the leaders of North Korea, Syria, Cuba and Venezuela, but faces practical and political limitations.

On Iran, Obama places more stress than Bush on negotiations and incentives to halt its nuclear program, but the outgoing president himself has belatedly shown the way, said Peter Beinart, a Council on Foreign Relations expert.

Aaron David Miller, a former adviser for both Republican and Democratic secretaries of state, said Iran presents the next US president with an "excruciatingly difficult" set of problems.

"Iran sits at the nexus of everything America cares about in this region: Iraq, Lebanon, nuclear proliferation, the Arab-Israeli issue," Miller told AFP.

Washington accuses Tehran of trying to sabotage US goals for stability in Iraq and Lebanon as well as US efforts to broker Arab-Israeli peace.

Miller says the next president will have a greater chance to broker peace between Israel and Syria than between Israel and the Palestinians, which are bogged down in both tough negotiations and internal divisions.

A "responsible, phased withdrawal" from Iraq

Having opposed the US-led invasion from the start, Obama seeks a "responsible, phased withdrawal" from Iraq — but US military commanders warn that security and political gains are fragile and reversible.

Obama aims to remove all combat brigades from Iraq by the summer of 2010.

He said Bush's invasion of Iraq distracted from Afghanistan, which he calls the central front in the war on terror because al-Qaeda used the country as a base to launch the 11 September, 2001 attacks on New York and Washington.

However, his policy lines are now little different from those of his Republican predecessor.

He has called for sending more US troops to Afghanistan to fight a resurgent Taliban and al-Qaeda and for launching pre-emptive strikes against militants across the border in Pakistan, a US ally that angrily opposes such action.

The Bush administration has launched such strikes already.

Obama has also backed calls by US military commanders for Washington to be prepared to talk with its enemies including Taliban elements in Afghanistan. The new president has promised to consult US allies more than Bush on key international issues.

But, like Bush, Obama is urging the European Union to send more combat troops to fight insurgents in Afghanistan and urged the Europeans to lift restrictions some Nato members have put on their troops on the ground.

Analysts like Justin Vaisse of the Brookings Institution believe that at the very least Obama will strike a friendlier chord in Europe than Bush, even if there are few practical changes.

On Russia, Obama has toughened his stance since giving an initially conciliatory reaction to Russia's 8 August military incursion into the territory of US ally Georgia.

More lately he has warned of a "resurgent and very aggressive Russia."

What do you make of Obama's historic victory? Would you have voted for him? Leave a comment below!

AFP