Less than two weeks after a watchdog report revealed the extensive classification of information about U.S. spending in Afghanistan, lawmakers are pressing Defense Secretary Chuck Hagel on why the data, which had long been a matter of public record, was suddenly made secret.

“The safety and security of U.S. and NATO forces in Afghanistan are paramount. However, inappropriately classifying information severely restricts the ability of Congress to conduct meaningful oversight and impairs the ability of the American people to know how billions of their taxpayer dollars are being spent in Afghanistan,” members of the House Oversight and Government Reform Committee wrote in a letter to Hagel Monday.