George Walker Bush is sworn in as the 43rd president of the United States pledging to "work to build a single nation of justice and opportunity", and outlining his main policy priorities, which include tax cuts and increased defence spending.

A row erupts between the US and China after an American spy plane is forced to make an emergency landing in the country following a mid-air collision with a Chinese fighter plane. The dispute simmers for three weeks until the US ambassador apologises for the accident, and Beijing agrees to hand back the crew and the damaged aircraft.

Terrorists fly hijacked passenger aircraft into the twin towers of the World Trade Center in New York, causing them to collapse. A third hijacked plane hits the Pentagon building in Washington DC, while a fourth crashes in rural Pennsylvania; in total some 2,793 people are killed in the worst-ever terror attack on US territory.

In response to the 9/11 attacks, President Bush declares a "war on terror", and identifies Osama Bin Laden's al-Qaeda network as responsible. A US-led coalition launches air-strikes against targets in Afghanistan, where Bin Laden is being sheltered by the Taleban regime.

Energy conglomerate Enron declares itself bankrupt with debts of some $31bn. It eventually transpires that CEO Kenneth Lay had fraudulently managed Enron's accounts, conspired to falsely inflate profits and hide accrued debt.

In his first State Of The Union address since taking office, President Bush identifies an "Axis Of Evil" - North Korea, Iraq and Iran - which he believes cast a malign influence over US interests.

Telecom company Worldcom files for bankrupcy citing losses of some $11bn - the largest such filing in US history. CEO Bernie Ebbers is eventually indicted on charges of fraud and conspiracy relating to the false financial reporting which led to the collapse.

President Bush signs a bill into law creating a huge new government department dedicated to preventing terror attacks on the United States. The Department of Homeland Security will have nearly 170,000 employees and merge the functions of 22 existing agencies - which have a combined budget of about $40bn.

The space shuttle Columbia breaks up as it re-enters the Earth's atmosphere, killing the seven astronauts on board. In a televised address, President Bush remarks: "These astronauts knew the dangers, and they faced them willingly, knowing they had a high and noble purpose in life."

After many months of UN diplomacy in an effort to avoid war, bombing of Iraq began. American forces began an air assault on Baghdad while British forces took action in the south of the country with the aim of taking Basra.

With the toppling of the regime of Saddam Hussein, President Bush declares that "major combat operations" in Iraq are over.

The naming of CIA agent Valerie Plame by columnist Robert Novak following an article by her husband, a former US diplomat, criticising the Bush administration's use of intelligence in the run up to the Iraq war triggers a bitter row over whether her name was disclosed deliberately by senior figures in the administration.

The publication of graphic images of prisoners being beaten and humiliated by US guards in Iraqi jails causes outcry around the world. President Bush condemns the guards' behaviour as unrepresentative; critics claim it was authorised at the highest level to "soften up" terrorism suspects.

In a damning report the Senate Intelligence Committee says the CIA overstated the threat posed by Iraq. As a result, the US and its allies went to war based on "flawed" information, the committee finds. There was, however, no evidence that the Bush administration had tried to coerce or officials to adapt their findings, it concludes.

The deaths of three soldiers in the Baghdad suburb of Sadr City, and another in a roadside bombing north of the capital, takes the American death toll in Iraq to 1,002. Acknowledging the death toll, Defense Secretary Donald Rumsfeld said that fighting terrorism "has its cost."

After a keenly fought campaign, President Bush sees off the challenge of Democrat John Kerry to secure a second term in the White House.

Hurricane Katrina triggers devastating flooding in the city, killing more than 1,000 people and leaving tens of thousands homeless. A delayed evacuation and ramshackle relief effort trigger stinging criticism of local, state and federal agencies.

The US military suffers its 2,000th death in Iraq. As protests and vigils are held nationwide and the names of the dead are read out on the floor of the House of Representatives, President Bush warns Americans to prepare for more casualties.