The in-tray: Momentous decisions loom on the first day at the office

When he walks into the Oval office as President for the first time this morning, Barack Obama will already have received an intelligence briefing on threats around the world. But with bodies still being pulled from the rubble of Gaza after three weeks of war and the truce between Israel and Hamas still fragile, one of his first presidential acts is expected to be the appointment of George Mitchell as his Middle East envoy.

The former senator helped negotiate peace in Northern Ireland as Bill Clinton's envoy and the appointment is a signal that Mr Obama, who has remained almost silent on the Gaza conflict, intends to plunge immediately into the turbulent waters of Middle East politics.

Even as he was delivering his inaugural address yesterday, the urgent and dauntingly heavy burdens of office were falling on Mr Obama's slim shoulders, along with the weight of global expectations that he must succeed where George Bush failed. Later today, Mr Obama is expected to instruct the Pentagon to end the war in Iraq and draw up plans for the orderly withdrawal of combat troops within 16 months.

At the stroke of noon yesterday, as George Bush's term of office expired, and power was being transferred to Mr Obama, a military aide standing near him received a briefcase with the codes needed to launch a nuclear strike.

At the same time, Mr Obama's most senior officials were being whisked in minivans from the swearing-in ceremony to newly vacated White House offices to take over the responsibilities running two foreign wars, protecting the country and staunching the bleeding economy.

These are anxious times and Mr Obama, who does not want to waste any more time after the anxious78-day wait of the transition period, has an ambitious first week ahead of him. Despite the huge economic problems facing America– he is said to be considering a major speech on the economy to the joint houses of Congress within weeks of taking office – foreign policy is expected to dominate the first few days in office.

On Iraq, he made clear his intentions months ago. "I intend to end this war," Mr Obama declared in July, " My first day in office, I will bring the Joint Chiefs of Staff in, and give them a new mission, to end this war responsibly and deliberately but decisively."

The new president is also due to convene his National Security Council where he is to demand a reassessment of the so-far failing strategy in Afghanistan, where he wants to send 30,000 more US troops.

Some time today he will hear from those members of Mr Bush's team who are remaining in their jobs. They include the Defence Secretary, Robert Gates, General David Petraeus, head of Central Command and General Raymond Odierno, US commander in Iraq.

The President is also expected to issue an executive order before the weekend, ordering the closure of the military prison at Guantanamo Bay. It will take months to be carried out as the new administration decides how to deal with about a dozen alleged hardened al-Qa'ida terroristsm, some of whom have been tortured by the US. It is not yet certain what sort of trials Mr Obama envisions and there are already difficulties in persuading other countries to take prisoners the US no longer wants.

An executive order banning torture, including the practice of waterboarding is also widely expected. Mr Obama also intends to reverse controversial policy dating back to Ronald Reagan, which bans US overseas aid going to any organisation that was in any way involved with abortion services.

Many of the actions were due to be taken before many of the White House staff had even been allocated desks – an indication of the hectic pace of activity of Mr Obama's national security advisers in the 78 day-transition since election day.

The first 100 or so days of the administration are the most difficult, because senior staff have yet to be confirmed in office – Hillary Clinton's confirmation should have occurred yesterday but was put off – and the full burden of decision-making falls on the president alone. During the election campaign Vice-President Joe Biden predicted that America's enemies will immediately seek to test Mr Obama. "Mark my words, it will not be six months before the world tests Barack Obama like they did John Kennedy," Mr Biden said on the campaign trail, "The world is looking. We're about to elect a brilliant 47-year-old senator president of the United States of America... Watch, we're gonna have an international crisis, a generated crisis, to test the mettle of this guy."

The young John F Kennedy faced similar problems immediately after he was inaugurated in 1961 as the Soviet Union sent missiles to Cuba and brought the world to the edge of nuclear Armageddon.