A new Executive Order signed by President Obama gives the US (specifically the President and Executive departments and agencies) the power to expropriate pretty much anything, anytime, for the purposes of national defense: “Under this order the heads of these cabinet level positions; Agriculture, Energy, Health and Human Services, Transportation, Defense and Commerce can take food, livestock, fertilizer, farm equipment, all forms of energy, water resources, all forms of civil transporation (meaning any vehicles, boats, planes), and any other materials, including construction materials from wherever they are available.”
There is an article on it here, and the Executive Order can be found on the Whitehouse website here.
