Confirmed, via my parents:
The University of Chicago Alumni of Washington are offering a Pentagon tour in August. Along with the usual information about security ("two forms of picture ID") is the following:
"English is the only language permitted inside the Pentagon. Please do not converse or otherwise communicate in any other language while on tour or you will be escorted out of the building."
Ay Caramba! This is un-American.
Where's Stephen Colbert when you need him?