Following the September 11, 2001, attacks on the United States by al-Qaeda, which was harbored by the Taliban in Afghanistan, NATO invoked Article 5 of its charter. This led to a multinational deployment of military personnel and civilians to Afghanistan from dozens of countries between 2001 and 2021.
Initially, the US military, CIA, and Afghanistan's Northern Alliance collaborated to remove the Taliban from power. Efforts then focused on pursuing al-Qaeda remnants, with British Royal Marines and UK Special Forces involved in mountain operations. Osama Bin Laden, the al-Qaeda leader, was located and killed by US Navy SEAL Team Six in Pakistan ten years later.
The initial phase of the US-led "Operation Enduring Freedom" was relatively calm. By late 2003, as US focus shifted to Iraq, Afghanistan was sometimes referred to as "Op Forgotten," yet remained dangerous. International forces, including Romanian troops, conducted patrols. Remote bases faced rocket attacks, attributed to local farmers potentially coerced or bribed.
A significant change occurred after 2006 when the UK deployed substantial forces to Helmand province. This area, previously more peaceful, experienced intensified fighting, with British paratroopers engaging in close-quarters combat against the Taliban.