Additional U.S. military civil affairs troops will be sent to Afghanistan and will work with the first U.S.-trained Afghan soldiers to help improve security, the U.S. government's coordinator for Afghanistan said Monday.

The lack of security remains a concern a year after the United States launched a war that toppled Afghanistan's Taliban rulers and dispersed the Al Qaeda terrorists they harbored.

But remaining pockets of insecurity are hampering efforts to rebuild the country and bring peace to Afghanistan's 26 million people after two decades of war.

U.S. Ambassador David Johnson said between 75 percent and 80 percent of Afghanistan "is already pacified" and in the remaining portion, in the southeast, U.S. forces are pursuing small groups of people "who continue to pose a threat."

He said one reason the Bush administration came up with the idea of expanding the military's civil affairs presence was the absence of any coalition offers to provide troops to expand the current international force now confined to Kabul.

The primary focus of U.S. troops has been fighting the remnants of Al Qaeda and the Taliban and the training of the fledgling Afghan army. In the middle of the year, the United States also sent civil affairs teams into the countryside to work with armed Afghan leaders in the regions to help provide greater security.

"The real security challenge is not so much in this city or that city, it's in the countryside as a whole," Johnson said at a briefing for a group of U.N. correspondents.

Currently, there are about 600 American civil affairs soldiers deployed in Afghanistan. Sometime early next year, the United States also plans to provide "some field training" for the Afghan soldiers it has been training by sending them out to work with the civil affairs units, Johnson said.

Despite criticism by some that the U.S. military should not do the work of aid organizations, the Army's Civil Affairs divisions have been actively involved in humanitarian projects.

They have visited villages to assess water, health, communications and infrastructure needs, conferred with international aid groups to determine pressing needs, and built and paid for schools, municipal buildings and other projects.