Kyle enlisted in the British Army in 2014, serving in the Duke of Lancaster's Regiment, spending four years before passing selection for Her Majesty's elite Special Air Service (SAS), where he is currently serving as a Sergeant for his sixth year. Tasked to Northern Ireland, Bosnia, Turkey, Iraq, Afghanistan, and Syria. Required to undergo resistance to interrogation (RTI) testing, Kyle was the only candidate in his class to escape the facility and evade capture.