The USA is the world's foremost economic and military power. On 11 September 2001, the USA was the subject of a massive terrorist attack by Al-Qaeda, when two hijacked aircraft were deliberately crashed into the World Trade Center in New York and a third into the Pentagon, the headquarters of the US Department of Defense, in Washington DC. A fourth hijacked aircraft crashed in Pennsylvania, killing everyone on board. Thousands of civilians were killed in the attacks, which were condemned by the UN Security Council (see Resolution 1368 of 12 September 2001).
The attacks had a huge impact on US foreign policy, with US President George Bush treating the attacks as acts of "war" and subsequently announcing a "war on terror" in response. In October 2001, the USA led a military campaign in Afghanistan to topple the Taliban regime which had sheltered Al-Qaeda leadership and training bases.
In March 2003, after a fractious series of debates within the UN Security Council in which the USA accused Baghdad of having weapons of mass destruction, a coalition of forces led by the USA invaded Iraq and overthrew the Ba'athist régime headed by President Saddam Hussein. No significant stockpile of such weapons was subsequently found. The US formally proclaimed an occupation administration, which included the legal application of the Fourth 1949 Geneva Convention.
On 1 May 2003, President Bush announced the end of major combat operations in Iraq, although subsequently a major insurgency took root. President Hussein was captured in Tikrit in December 2003 by the US army and thereafter put on trial by an Iraq court. The conduct of the trial and the subsequent hanging of the former President were widely critised.
As of August 2008, tens of thousands of US troops continued to be engaged in military operations in both Afghanistan and Iraq. Those operating the US military prison at Guantanamo Bay on the island of Cuba have been widely criticised for the abusive treatment of detainees (so-called enemy combatants). On 22 January 2009, President Obama issued an executive order requiring the closure of the Guantanamo facility within one year.
In September 2008, General David Petraeus, then-commander of the multi-national forces in Iraq, was appointed to head US Central Command. General Petraeus is credited with designing and executing a counter-insurgency 'surge' of US troops into Iraq. Policymakers are re-focusing on the situation in Afghanistan, which has deteriorated to its worst since the overthrow of the Taliban. In June 2010, General Petraeus assumed the command of US troops in Afghanistan, replacing General McChrystal.
With the election of the new US administration, a number of new foreign policy steps have been announced. It includes among others, to responsibly end the war in Iraq entailing removal of all US troops from Iraq by the end of 2011 and a new strategic approach to Afghanistan, combining a regional approach of eliminating terrorism with a focus on building capacity of the Afghan counterparts to enable them to take over responsibility for the security of Afghan people. As of March 2011, the US was part of a coalition engaged in military operations against Libya (see Current conflicts section)