Here are a few key figures about the conflict, which a historic agreement between Washington and the Taliban seeks to end:

- Boots on the ground -

The NATO alliance committed to the Afghan conflict in December 2001, but the United States has always provided the largest military contingent. At its peak, under president Barack Obama in 2011, the US had 98,000 personnel on the ground, according to Pentagon figures.

As of February 2020, there are about 16,500 military personnel from 38 countries in Afghanistan as part of NATO's Operation Resolute Support, according to the latest data from the alliance.

Officially, that mission is now only for training and support of the Afghan army.

The United States makes up roughly half of the force with 8,000 soldiers, followed by Germany (1,300), Britain (1,100), Italy (900), Georgia (870) and Romania (800).

France, which has 4,000 soldiers in Afghanistan in 2010, pulled out of the country in 2012.

Beyond the US participation in Resolute Support, there are several thousand US forces on the ground taking part in Operation Freedom's Sentinel.

The Pentagon does not provide exact figures for that anti-jihadist mission, but it estimates the total US deployment in Afghanistan at "about 14,000."

President Donald Trump has often mentioned 13,000 as a total figure.

- Losses -

The United States has paid the highest price in terms of foreign fatalities in Afghanistan, with 1,909 military personnel killed and more than 20,700 wounded as of February 20, the Pentagon says.

As for other NATO coalition members, Britain has lost 454 personnel, followed by Canada (157) and France (89 dead), according to icasualties.org, which monitors the dead and wounded in the conflicts in Afghanistan, Iraq and Syria.

The Afghan government no longer publishes data for losses within its army, which are significant. The United Nations estimates that 32,000-60,000 Afghan civilians have been killed in the conflict.

- How much does the war cost? -

As of September 30, 2019, the Pentagon officially estimated the cost of US operations in Afghanistan at $776 billion since 2001. Of that total, $197.3 billion has been earmarked for reconstruction of the war-ravaged country and its institutions.

But according to a study done by Brown University and published late last year, the cost of America's wars exceeds the Pentagon's estimate, as State Department aid is not taken in account, nor are any intelligence operations or the medical costs of wounded veterans.

Factoring in all those costs, the Brown researchers say the US "wars on terror" in Iraq, Syria and Afghanistan since 2001 have cost $6.4 trillion.