Provision of the data was delayed because of its classified nature, a board official said.

He and other investigators refused to provide more details of the problem, citing the classified nature of the system.

This is further complicated by the classified nature of intelligence funding.

The 556th flew various electronic warfare and special operations sorties of a classified nature.

The officials who described the new assessment said they could not be identified by name because of the classified nature of the document.

He refused to give details, citing the program's highly classified nature.

It bore the logo of the Senate and several warnings of a classified nature.

"I can't remember the last time we saw anything of a classified nature from Washington," one of the agency's senior officials said.

Initially held up because of its classified nature, this was eventually granted in 1946.

Still, material shown during the trial was shielded from courtroom spectators because of its classified nature.