THIS MORNING’S KILLING of al-Qaeda leader Osama bin Laden marks the latest significant milestone in the United States’ ‘War on Terror’ – a series of foreign policy actions aimed at neutralising the apparent threat posed to the western world by extremist terrorists.

Here, in numbers, is a selection of statistics on the September 11 attacks that triggered the invasion of Afghanistan, and of the events that have followed.

19 – The number of hijackers involved in the September 11, 2001 terrorist attacks; in 2006, Osama bin Laden claimed direct responsibility for their actions.

2,996 – The total number of casualties on 9/11, including the 19 hijackers. They include:

• 2,606 people – including civilians and emergency service workers – killed at the Twin Towers of the World Trade Centre in New York
• 87 passengers on board American Airlines flight 11, which struck the WTC’s North Tower at 8:46am
• 60 passengers on board United Airlines flight 175, which struck the South Tower 17 minutes later
• 411 emergency workers, including 343 firemen and 60 police officers who had entered the WTC buildings after they had been struck
• 59 passengers on American Airlines flight 77, which struck the Pentagon
• 125 people who were inside the Pentagon at the time
• 40 passengers on board United Airlines flight 93, which crashed at Shanksville in Pennsylvania
• The total does not include those who died from secondary causes arising from the attacks, such as pulmonary problems or suicide

70 – The number of countries – including Ireland – whose citizens were killed in the 9/11 attacks.

26 – The number of days between the 9/11 attacks and the first United States-led military action in Afghanistan on October 7, 2011.

2,441 – The total number of military casualties in Afghanistan to date.

4,770 – The total number of military casualties in Iraq to date.

543 – The total number of UK military deaths arising from the two campaigns.

107,369 – The total number of documented civilian deaths in Iraq, up to October 10, 2010, as disclosed by the United States.

15,114 – The number of previously undisclosed civilian deaths revealed in the US war logs published last year by WikiLeaks.

(0 – The number of people who can access the WikiLeaks logs as of the time of publication; the server on which they were stored appears to have gone offline, with all pings timing out.)

654,965 – The number of ‘excess deaths’ of civilians in Iraq between March 2003 and mid-2006, as estimated by the Lancet medical journal. More recent estimates from other sources put the figure at over a million.

550 – The amount, in tons, of yellowcake uranium stockpiled by Iraq in 1990, included in a dossier of that country’s apparent Weapons of Mass Destruction prior to the beginning of the military campaign there in 2003.

0 – The amount of uranium (or, indeed, any other WMDs) actually found in Iraq.

55 – The number of senior officials in the administration of Saddam Hussein, as identified in various editions of the US’s ‘personality identification playing cards’.

10 – The number of those officials who are still at large.

400 billion – The estimated amount, in United States dollars, spent by the US on its military operations in Afghanistan to date.

787 billion - The estimated amount, in United States dollars, spent by the US on its military operations in Iraq to date.

550 – The maximum amount, in United States dollars, for which an unemployed person in the state of Connecticut can claim unemployment benefit each week (payable depending on their previous earnings and the number of dependents they support).

2,160,992,260 – The number of weeks’ unemployment benefit (paid at the maximum level) that could have been covered for the same price as the running cost of the military campaigns in Iraq and Afghanistan.

52.9 per cent - The number of US voters who voted for Barack Obama to become president in October 2008.

262 – The number of days between Barack Obama assuming the office of President of the United States and being announced as the winner of the 2009 Nobel Peace Prize.

46 per cent – The number of voters who approved of Obama’s job performance, under a poll published yesterday by Gallup. Exactly the same amount of respondents disapproved of his job performance; the remaining 8 per cent were undecided.

3,520 – The number of days between the September 11 terrorist attacks and the death of Osama bin Laden.

1,185 – The number of people who died on September 11 whose bodies have yet to be recovered or identified.