WASHINGTON - The United States is expected to designate Iran's Revolutionary Guards Corps a foreign terrorist organization, three U.S. officials told Reuters, marking the first time Washington formally labels another country's military a terrorist group.

The decision, is expected to be announced by the U.S. State Department, perhaps as early as Monday, the officials said.

U.S. Secretary of State Mike Pompeo, a strident Iran hawk, has advocated for the change in U.S. policy as part of the Trump administration's hardening posture toward Tehran.

It would come ahead of the first anniversary of President Donald Trump's decision to pull out of an international nuclear deal with Tehran and reimpose sanctions that had crippled Iran's economy.

The administration's decision to make the designation was first reported by the Wall Street Journal. Reuters