The 1977 International Emergency Economic Powers Act allows the government to freeze assets , limit trade and confiscate property in response to an " unusual and extraordinary threat " to the United States that originates substantially outside of it . As of 2015 more than twenty emergencies under the IEEPA remain active regarding various subjects , the oldest of which was declared in 1979 with regard to the government of Iran . Another ongoing national emergency , declared after the September 11 attacks , authorizes the president to retain or reactivate military personnel beyond their normal term of service
September 11 attacks
September 11 attacks
State of emergency