In a letter to U.S. Defense Secretary Leon Panetta, lawyers for the defendants say televising the trial is the only way to dispel what they call "pervasive" mistrust of American military tribunals.
Lawyers previously asked a military judge to allow television coverage. But the judge said Panetta would have to approve it.
A Pentagon spokesman, Army Lt. Col. Todd Breasseale, says Panetta has not yet considered the request. The letter was sent Thursday.
The public can watch the hearings at the U.S. base in Cuba by closed-circuit TV at Fort Meade, Maryland. The Sept. 11 trial is more than a year away.