WASHINGTON (AP) _ The Defense Department's newest security recruits demonstrated Tuesday they know how to take orders _ even if they grumble about it.

``Sit! Sit!'' officer William Lagasse yelled and Woodan, a bomb-sniffing German shepherd assigned to the Pentagon, obediently rested on his haunches. But Woodan _ pronounced Woo-Dan _ wouldn't stop growling at one of his new partners, a dog named Johnny, who was being good beside his handler, officer Lynne Mueller.

``He's real friendly to people,'' Lagasse said with a smile, hanging tight to Woodan's straining leash as the canine security crew was introduced at a Pentagon briefing.

Woodan and Johnny and two other dogs, Bak and Benny, were sworn in Tuesday as the newest members of the Defense Protective Service, the Pentagon's police force, after graduating Sept. 18 from a military police dog training school at the Lackland Air Force Base, San Antonio, Texas. Johnny and officer Mueller finished first in their class.

The German shepherds, who together cost $15,000, will be on patrol at the Pentagon from 6 a.m. until 6 p.m., working in two-dog teams in overlapping eight-hour shifts, and sniffing around vehicles, equipment and materials coming into the building each day.

Previously, the Pentagon didn't have canines assigned to the massive building and had to call in dogs from other military services during bomb drills or threats or other alerts and when high level visitors came to see Defense Secretary William Cohen.

John Jester, chief of the Defense Protective Service, said establishing the K-9 unit at the Pentagon is part of an overall move to tighten security in an age when there are increasing international and domestic terrorist worries.

``It is not the result of any specific threat,'' Jester said. ``This step is one of many proactive and prudent measures we are taking to minimize the occurrence of a possible tragedy.''

Marine Sgt. Vance Dunlap, supervisor of the Pentagon's K-9 crew, said the dogs are starting their military careers at the bottom: ``They're privates right now.''