war period
(3) For purposes of section 231b(i)(2) of this title , a “war period” shall be deemed to have begun on whichever of the following dates is the earliest: (A) the date on which the Congress of the United States declared war; or (B) the date as of which the Congress of the United States declared that a state of war has existed; or (C) the date on which war was declared by one or more foreign states against the United States; or (D) the date on which any part of the United States or any territory under its jurisdiction was invaded or attacked by any armed force of one or more foreign states; or (E) the date on which the United States engaged in armed hostilities for the purpose of preserving the Union or of maintaining in any State of the Union a republican form of government.