It would have had to have two -- for single quotes. And two for full quotes, one beginning and one ending.
"It was highly out of the ordinary for an organization, even the Air Force, to have proportional-spaced fonts for someone to work with," said Allan Haley, director of words and letters at Agfa Monotype in Wilmington, Mass. "I'm suspect in that I did work for the U.S. Army as late as the late 1980s and early 1990s and the Army was still using [fixed-pitch typeface] Courier."