[15] Promoted to lieutenant colonel on 30 June 2001,[16] Carleton-Smith became Military Assistant to the Commander-in-Chief, Land Forces,[12] becoming Commanding Officer of 22 Special Air Service Regiment in 2002.

After serving during the 2003 invasion of Iraq and also during operations in Afghanistan,[13] he was advanced Officer of the Order of the British Empire (OBE) on 23 April 2004.

[17] Promoted colonel on 30 June 2005,[18] he became Deputy Director Policy Planning at the Ministry of Defence at that time.

[20] In August 2008 he led Operation Eagle's Summit, which involved a daring foray into Taliban territory.

[24] In July 2022, the BBC published a report alleging evidence that "SAS operatives in Afghanistan repeatedly killed detainees and unarmed men in suspicious circumstances," while Carleton-Smith, then Director Special Forces, "failed to pass on evidence to [the] murder inquiry"[25] which was being conducted by the Royal Military Police.