President Donald Trump ordered government agencies on Monday to propose revoking two regulations for each new one they issue, fulfilling a promise he made shortly after his election.

The military and regulations related to national security will be exempt from the executive action, administration officials familiar with the action said. They requested anonymity to discuss the action before Trump had signed it.

"It's going to be hard to implement, just because changing rules involves going through detailed administrative processes and soliciting public comment," said Darrell West, director of governance studies at the Brookings Institution in Washington. "So it's not a situation where an agency head can come in and kill a regulation overnight."