Instances in which Congress reserves the right by concurrent resolution to declare terminated the conditions authorizing executive action are fewer. In a 1941 statute the Secretary of the Navy was authorized to establish a plant protection force for naval shore establishments and to maintain and operate this force until June 30, 1943, unless Congress at an earlier date, by concurrent resolution, declared such force no longer necessary.[619] A 1942 amendment to the Communications Act of 1934 gave the President certain powers to control wire communication facilities upon proclamation by the President that a state or threat of war exists involving the United States. The President’s powers in this respect were to end not later than six months after the termination of such state or threat of war and not later than such earlier date as the Congress by concurrent resolution may designate.[620] In defining national emergency for purposes of the Federal Civil Defense Act of 1950,[621] Congress stipulated that “the provisions of this title shall be operative only during the existence of a state of civil defense emergency.... The existence of such emergency may be proclaimed by the President or by concurrent resolution of the Congress if the President in such proclamation, or the Congress in such resolution, finds that an attack upon the United States has occurred or is anticipated and that the national safety therefore requires an invocation of the provisions of this title.” Congress also has reserved the right, although not on an exclusive basis, to determine by concurrent resolution the “dates of commencement and termination of an armed conflict.”[622] _Enabling or Requiring Executive Action_: An example of the use of the concurrent resolution as an enabling device is the provision of the Neutrality Act of 1939,[623] which imposed rigorous limitations upon United States carriage to belligerents “whenever the President, or the Congress by concurrent resolution, shall find that there exists a state of war between foreign states.”