United States territorial acquisitions
The Panama Canal Zone was an unorganized US territory located within the Republic of Panama. It was established under the Hay–Bunau-Varilla Treaty in 1903 and disestablished in 1979 under the Torrijos–Carter Treaties. Panama gained full control over the Panama Canal in 1999.
Dennis DeConcini
DeConcini sponsored an amendment (the DeConcini Reservation) to the Panama Canal Treaty of 1977 which allows the United States "to take such steps as each [the U.S. or Panama] deems necessary, in accordance with its constitutional processes, including the use of military force in the Republic of Panama, to reopen the Canal or restore the operations of the Canal, as the case may be."