The US-led military coalition has officially ended combat operations in Afghanistan's volatile Helmand province.
US marines and British troops handed over their joint bases of Camp Leatherneck and Camp Bastion to Afghan security forces as the protracted mission winded down.
The operation began in October 2001. US and British forces were dispatched to Afghanistan less than a month after the September 11 attack on New York's World Trade Centre.
The beginning of then US President George Bush's so-called War on Terror. The supposed aims at that time: To defeat the Taliban, deprive Osama bin Laden's al-Qaeda a safe haven, and to cut opium production.
The success or otherwise of that campaign is still the subject of much debate. And 13 years on, the War on Terror is still being waged on multiple fronts.
But what is the underlying justification, the rationale behind a largely military strategy, and is it a fight that can ever be won?
Presenter: Sami Zeidan
Afzal Ashraf - a security analyst and consultant fellow at the Royal United Services Institute.
Phyllis Bennis - a director at the Institute for Policy Studies, and author of the book Ending the Iraq War: A Primer.
Davis Lewin - deputy director at the Henry Jackson Society.
Source: Al Jazeera