Whoever intentionally destroys, impairs, injures, interferes or tampers with real or personal property with reasonable grounds to believe that such act will hinder, delay or interfere with the preparation of the United States, or of any state, commonwealth, territory or island possession of the United States, for defense or for war, or for the prosecution of war by the United States, shall be fined not more than $2,000 or imprisoned not more than 10 years, or both.