Whenever the President, or the Congress by concurrent resolution, shall find that there exists a state of war between foreign states, and that it is necessary to promote the security or preserve the peace of the United States or to protect the lives of citizens of the United States, the President shall issue a proclamation naming the states involved; and he shall, from time to time, by proclamation, name other states as and when they may become involved in the war.
22 U.S. Code § 441 - Proclamation of state of war between foreign states
Joint Res. Nov. 4, 1939, ch. 2, § 19, 54 Stat. 12, provided that: “The joint resolution of August 31, 1935, as amended [sections 245a to 245i of this title], and the joint resolution of January 8, 1937 [ch. 1, 50 Stat. 3], are hereby repealed; but offenses committed and penalties, forfeitures, or liabilities incurred under either of such joint resolutions prior to the date of enactment of this joint resolution [this subchapter] may be prosecuted and punished, and suits and proceedings for violations of either of such joint resolutions or of any rule or regulation issued pursuant thereto may be commenced and prosecuted, in the same manner and with the same effect as if such joint resolutions had not been repealed.”
Neutrality Act of 1939 not to be deemed repealed or modified in any manner by Joint Res. May 7, 1940, ch. 185, 54 Stat. 179, according to section 3 thereof, which resolution amended section 5(b) of the Trading With the Enemy Act, see section 4305(b) of Title 50, War and National Defense, which resolution approved and confirmed Ex. Ord. No. 8389, amending Ex. Ord. No. 6560, formerly set out as a note under section 95a of Title 12, Banks and Banking, and regulations and general rulings issued by Secretary of Treasury under Ex. Ord. No. 8389.
Joint Res. Nov. 4, 1939, ch. 2, § 17, 54 Stat. 12, provided that: “If any of the provisions of this joint resolution [this subchapter], or the application thereof to any person or circumstance, is held invalid, the remainder of the joint resolution, and the application of such provision to other persons or circumstances, shall not be affected thereby.”
Joint Res. Nov. 4, 1939, ch. 2, 54 Stat. 4, provided in part as follows:
“Whereas the United States, desiring to preserve its neutrality in wars between foreign states and desiring also to avoid involvement therein, voluntarily imposes upon its nationals by domestic legislation the restrictions set out in this joint resolution [this subchapter]; and
“Whereas by so doing the United States waives none of its own rights or privileges, or those of any of its nationals, under international law, and expressly reserves all the rights and privileges to which it and its nationals are entitled under the law of nations; and
“Whereas the United States hereby expressly reserves the right to repeal, change or modify this [this subchapter] or any other domestic legislation in the interests of the peace, security or welfare of the United States and its people.”