"This is a move we consider it prudent to make in the present circumstances," he said.
Assessment on the need to continue mobile patrols and the accompanying of police patrols by troops would be kept under constant review, he said.
The move followed the withdrawal of 250 troops from Northern Ireland last week - the first since the IRA renewed its ceasefire in July. Members of the 3rd Battalion the Parachute Regiment were switched from their base in North Belfast to the Maze prison before the bulk of them returned to base England. The rest were put on guard duty at the top security jail.
The move follows several months of complaints from republican and other sources that the security forces had not reacted quickly enough to the IRA cessaton of violence.
Security has been reduced, but many observers believe the run down has taken place at a slower rate than that which followed the first IRA ceasefire in August 1994.
Sinn Fein hascomplained that house searches, arrests and other security force activity had been running at a high level.
The security forces responded that the measures were being tailored to meet the level of threat from both loyalist and republican sources.
The three major paramilitary groups - the IRA, the Ulster Volunteer Force and Ulster Defence Association - have all declared ceasefires but smaller organisations on both sides of the divide have yet to do so.Reuse content