Why is Britain in Afghanistan?

The British and American presence in Afghanistan was triggered by the attacks on the US mainland on 11 September 2001.

The UK, led at the time by Prime Minister Tony Blair, lost 67 people on 9/11, more than any other country apart from the US. In the aftermath of the attack, Tony Blair was vociferous in his support for the United States, gaining considerable popularity there as a result.

It was probable, then, that the UK would participate alongside the United States in any military military retaliation against the perpetrators of the attacks on the World Trade Center and the Pentagon.

In terms of its domestic politics, the United States needed to be seen to respond aggressively to the al-Qaida-led incursions onto its territory. This was not the case in the United Kingdom.

And so it happened that when a Nato force went into Afghanistan in October 2001, the UK contingent was larger than any other, barring the US. At the time there was little domestic opposition in either the United Kingdom or the United States.

The total number in Afghanistan in November 2001, including US and allied troops, was small by today's levels - a paltry 1,300.

In 2001 Tony Blair explained that the invasion was necessary to eliminate the "terrorist threat" and the heroin supply (Afghanistan supplies 90 per cent of the world's heroin). "Our aim is to shut down the terrorist network," he said. Al-Qaida's leader, Osama bin Laden, was thought to have his base somewhere in Afghanistan.

In 2004 Tony Blair refined the argument for a UK presence in Afghanistan, suggesting a terrorist link between Afghanistan and Iraq (both the US and the UK were by 2004 deeply involved in the Iraq war). Meanwhile, coalition military casualties in Afghanistan between 2001 and 2005 remained at a consistent, low level.

The then British defence secretary, John Reid, appeared in 2006 to evolve the argument for a coalition troop presence in Afghanistan by saying that it was there "to create... a framework of society for Afghanistan institutions".

Reid was articulating a view that Afghanistan, which had known conflict on its territory for several decades, could only find peace if a majority of the population bought into what had been, until recently, a failed state.

And in geopolitical terms, a more stable Afghanistan might be less inviting to the many militant Muslims based in and around towns in northern Pakistan.

By 2009 Britain's justification for having what was by now a sizeable force in the country - over 9,000 appeared to have come full circle, with Defence Secretary Bob Ainsworth explaining that we were there "as a result of our assessment of the terrorist threat facing Britain".