The judge wears a black robe and sits in front of an American flag.

But little else in the windowless, cramped office in Building A at the Army's Arlington Hall Station resembles a traditional courtroom.

There, in one of the military's most secure intelligence bases, a former head of an Army special operations division is being court-martialed under elaborate security measures. Most of the testimony has been secret, and the Army, citing national security concerns, will not release the names of some witnesses.

Col. James E. Longhofer, who from 1981 to 1982 headed the division that conducted covert missions for the Army, is accused of disobeying a lawful order, dereliction of duty and conduct unbecoming an officer. He has denied the charges.

His court-martial, which began Monday and is expected to extend into next week, is the second of five stemming from a two-year investigation into what prosecutors have alleged was improper spending and accounting by some of the Army's special operations units. The first court-martial ended in an acquittal last December for Master Sgt. Ramon Barron; three other trials are pending.

The probe has been criticized by some who say it has gone on too long and is being pressed by senior Army officers uncomfortable with the service's involvement in covert activities. Its defenders say the trial will help control soldiers who "got carried away" and failed to account properly for the government funds they used for clandestine operations.

None of the charges against Longhofer, an intelligence officer, allege financial misconduct.

Military judge Col. James E. Noble's makeshift courtroom, so compact that witnesses sit about six feet from the military jury, was established at Arlington Hall, which houses the Army's Intelligence and Security Command, to ensure tight security. Coded electronic locks bar the courtroom doors, and background music camouflages conversation in an anteroom where a red-lettered sign warns: "Do Not Discuss Classified Information in This Room."

Noble has said he wants the trial to be as open as possible, but so far only one of about a dozen witnesses has testified in open session.

Among those testifying in secret was Gen. Fred K. Mahaffey, head of the Florida-based U.S. Readiness Command. Longhofer is charged with being derelict by failing to report to Mahaffey allegations of financial misconduct by a subordinate in 1983. At the time, Mahaffey was Longhofer's superior as deputy chief of staff for operations and plans.

The junior officer, Lt. Col. Dale E. Duncan, was found guilty last month in federal court of theft and making false statements. Duncan, who is free on bond pending appeal, has been sentenced to a year in prison.

Prosecutors have also alleged that Longhofer offered Duncan's secretary, who was earning $18,000 annually, a $36,000-a-year job "in hopes that she would remain silent" about the allegations against Duncan, according to his charge sheet.

Darlene Bell testified in open session Thursday that Longhofer offered her the job because "he said I was a very loyal person." She replied "no" when Noble asked her if "anyone indicated that this job offer was dependent on keeping silent about [Duncan's] problems."