NATO Secretary-General Anders Fogh Rasmussen says coalition forces will continue to fight alongside Afghan forces as the security transition takes place in Afghanistan.

Rasmussen said Friday while the United States, France and other NATO allies move from a combat to a support and training role in 2013, the shift will be gradual and not amount to disengagement from combat.

The NATO chief spoke as a two-day meeting of NATO defense ministers concluded in Brussels.

U.S. Defense Secretary Leon Panetta and French President Nicolas Sarkozy have each suggested the coalition should end its combat role in 2013. Mr. Sarkozy recently announced that his country would withdraw its combat forces from Afghanistan in 2013 — a year earlier than planned.

NATO'S plan is to hand full security responsibility to Afghan forces at the end of 2014.

On Friday, the defense ministers discussed the size and cost of the Afghan force after foreign combat troops leave.

The Afghan army and police are expected to grow to about 350,000 members, but French Defense Minister Gerard Longuet said the future size of the force could be smaller — closer to 230,000.

The annual cost of maintaining such a force is estimated to be around $6 billion.

NATO leaders are due to decide on the cost and size of maintaining Afghan forces at a summit set for May in the U.S. city of Chicago.

Also Friday, Secretary-General Rasmussen announced NATO ministers have agreed to buy five reconnaissance drones for the alliance's new Ground Surveillance system. Thirteen countries are participating in the project.

The NATO chief said the system will give alliance commanders “the ability to see what is happening on the ground, at long range, over periods of time, around the clock, in any weather.”

The reconnaissance drones made by U.S. firm Northrop Grumman fly at high altitudes and can stay in the air for over 24 hours.