In his May 11 letter, William Winkenwerder Jr., assistant secretary for health affairs at the Defense Department, said that a Physicians for Human Rights report on psychological torture by U.S. forces relied on "unsubstantiated allegations" about military physicians.

That report, "Break Them Down," detailed the use of techniques such as sleep deprivation and isolation. In a section on health professionals, it cited sworn testimony by Col. Thomas M. Pappas that physicians were asked to approve interrogation plans; internal FBI e-mails that substantiate the existence of psychologist-psychiatrist teams formed to facilitate interrogation; and Maj. Gen. George Fay's findings that medical personnel were aware of abuse but failed to report it. Moreover, the Pentagon has never denied that physicians at Guantanamo Bay, Cuba, shared medical records with interrogators.

Mr. Winkenwerder's letter underscored the urgent need for Congress to establish a broad and independent investigation into the growing allegations of mistreatment of detainees in U.S. custody, including the possible complicity of medical personnel.

Without a doubt most military medical personnel in Iraq, Afghanistan and Guantanamo have acted honorably. But a structure must be put into place to protect them from being instruments of abuse.

LEONARD S. RUBENSTEIN

GRETCHEN BORCHELT

Washington

The writers are, respectively, executive director and a former Jonathan Fine fellow at Physicians for Human Rights.