Goeff Hoon announced that the UK forces in the Afghanistan peacekeeping program will be reduced from 1,300 to approximately 400 troops.
The 1,700-strong Royal Marines battle group deployed to hunt down al Qaida fugitives will also leave, under a phased “drawdown” beginning next month.
Mr Hoon said the UK would maintain a Tomahawk-armed submarine presence, ships, aircraft and elements of other forces in Afghanistan and the region.
His statement came after leadership of the International Security Assistance Force (ISAF) was handed over to Turkey earlier today.
Mr Hoon denied that the reduction in British troops meant a reduction “in our commitment either to Afghanistan or the campaign against international terrorism”.
He said: “In fact, it is proof of our willingness to keep up military action for as long as it takes. This is not a conventional campaign. It will vary in tempo and location.”
Shadow defence secretary Bernard Jenkin welcomed the troop reduction and congratulated the armed forces on “a job well done”.