Mr Bloomberg cited concerns over some proprietary business information that may be contained within his tax returns.

BBC: Bloomberg spends mightily in New York

These include the heightened risk of industrial espionage during inspections and the possible loss of proprietary business information through other means.

CENTERFORSECURITYPOLICY: Center for Security Policy | EXCERPTS OF TESTIMONY BY FRANK J. GAFFNEY, JR. before the SENATE ARMED SERVICES COMMITTEE

Indirect costs will likely include the loss of proprietary business information during intrusive inspections by international monitors and lost production time due to these inspections -- that may take as long as ten business days.

CENTERFORSECURITYPOLICY: Center For Security Policy