The longest war in American history has gone on for more than 18 years. The US and its NATO-led allies announced the official conclusion of their combat mission in Afghanistan in 2014.
But with the country remaining in violent turmoil, plans for the exit of the coalition have been repeatedly put off. US President Donald Trump has expressed an eagerness to withdraw his country's forces, which make up about 13,000 of the almost 23,000 foreign troops there.
His government is pursuing a peace deal with the Taliban, the Islamic fundamentalists who once ruled the country and have reclaimed significant patches of it.
The US said in late February that, conditional on a week-long reduction in violence, it would sign a peace agreement with the Taliban paving the way for a US troop withdrawal and new talks between the Taliban and the Afghan government.
The plan was a gamble that Afghanistan's President Ashraf Ghani, who was declared the winner of a disputed 2019 election, will retain enough authority to pull together representatives for such an intra-Afghan dialogue. Ghani's rival, chief executive Abdullah Abdullah, has accused Ghani of rigging the vote and declared himself the victor.
The Taliban has also rejected the outcome of the vote, saying it had no legitimacy because it was conducted under the "umbrella of occupation." Despite the US having spent an estimated $900 billion on the Afghan conflict, the Taliban are at their strongest since being ousted from power.
The group controls or contests about half the country and regularly stages attacks in Kabul. The Afghan military, which receives training and advice from the US and its allies, has been hampered by insufficient air power and heavy combat losses and desertions.
In 1989, the Soviet military pulled out of Afghanistan, after a decade-long occupation that had made the country a front line in the Cold War.
The US, which actively supported the Soviets' opponents, including radical Islamist factions, also disengaged. Bloody chaos followed until the Taliban seized the capital Kabul from the feuding warlords who had all but levelled it.
The Taliban imposed stern theocratic rule and gave the terrorist group al-Qaeda a base. In 2001, after the Taliban refused to extradite al-Qaeda leader Osama bin Laden following his group's Sept. 11 attacks on the US, the US invaded Afghanistan.
When bin Laden and the Taliban leadership fled, the US mission morphed into a nation-building undertaking — but with limited military resources, as the US focused on a separate war in Iraq. Eventually, more than 50 nations joined the coalition led by the North Atlantic Treaty Organization.
In 2009, US President Barack Obama ordered a "surge" in forces that reached a peak of 140,000 in 2011. Military commanders reported progress on the ground, but war fatigue at home, especially after the killing of bin Laden in Pakistan, led Obama to start winding down the American troop presence.
Doubts that the Afghan military could stand on its own prompted him to leave the last of them in place when he turned the presidency over to Trump in January 2017.
Within a year, Trump had deployed an additional 3,500 US troops to the country at the Pentagon's urging. An estimated 212,000 people have been killed in the conflict in Afghanistan and neighbouring Pakistan.
There's widespread agreement in the US that the war against the Taliban can't be won militarily. The US commander in charge of American and coalition forces, General Scott Miller, said just that in an interview with NBC in late 2018.
There are divisions, however, over how fast and under what conditions the US should exit the fight. On one end are those who say it's important to first negotiate a political agreement that would constrain the Taliban in the event they regain power.
In this scenario, the Taliban would pledge to never again allow a global terrorist threat to emanate from Afghanistan and to respect the country's current laws and constitution, that is, refrain from reinstituting strict Islamic law. On the other end are those who say such assurances from the Taliban would be meaningless.
Some who hold this position say the priority should be to stop pouring lives and money into remaking Afghanistan when it isn't working and wasn't the original motivation for the war. Others argue it's too dangerous to leave Afghanistan with the Taliban as strong as they are and the Afghan forces as weak.
Disclaimer: This article first appeared on Bloomberg.com, and is published by special syndication arrangement.