The war in Afghanistan - the longest in American history - has changed markedly since US president Barack Obama took office in January 2009. Troop levels remained roughly constant under his predecessor, former president George Bush, with around 30,000 American troops deployed in Afghanistan; the number of coalition military deaths also remained bracketed between 150 and 300.

Since Obama took office, both the American "footprint" and the level of violence have incresed sharply.

Troop levels by month

The "surge" announced by Obama in late 2009 was actually the second of his presidency. Shortly after taking office, Obama ordered more troops to Afghanistan, bringing US troop levels from roughly 33,000 in January 2009 to more than 67,000 by year's end. Obama would order another 30,000 troops into Afghanistan in 2010, bringing total troop levels to roughly 100,000.

US military deaths by year

2010 was by far the deadliest year for coalition troops in Afghanistan, with 711 total fatalities, a 36 per cent increase from the previous year.

Coalition deaths by province

Most coalition deaths in Afghanistan have been concentrated in the south. Helmand province has been by far the deadliest, accounting for more than 25 per cent of total fatalities, followed by Kandahar, the birthplace of the Taliban movement.