The sequence was first the United States declared war on the Empire of Japan on December 8, 1941. This was in response to the attack on Pearl Harbor the previous day, December 7, 1941.
JOINT RESOLUTION Declaring that a state of war exists between the Imperial Government of Japan and the Government and the people of the United States and making provisions to prosecute the same.
Whereas the Imperial Government of Japan has committed unprovoked acts of war against the Government and the people of the United States of America:
Therefore be it Resolved by the Senate and House of Representatives of the United States of America in Congress assembled, That the state of war between the United States and the Imperial Government of Japan which has thus been thrust upon the United States is hereby formally declared; and the President is hereby authorized and directed to employ the entire naval and military forces of the United States and the resources of the Government to carry on war against the Imperial Government of Japan; and, to bring the conflict to a successful termination, all the resources of the country are hereby pledged by the Congress of the United States.
On 11 December 1941, Nazi Germany declared war against the United States.
MR. CHARGE D'AFFAIRES:
The Government of the United States having violated in the most flagrant manner and in ever increasing measure all rules of neutrality in favor of the adversaries of Germany and having continually been guilty of the most severe provocations toward Germany ever since the outbreak of the European war, provoked by the British declaration of war agains Germany on September 3, 1939, has finally resorted to open military acts of aggression.
On September 11, 1941, the President of the United States publicly declared that he had ordered the American Navy and Air Force to shoot on sight at any German war vessel. In his speech of October 27, 1941, he once more expressly affirmed that this order was in force. Acting under this order, vessels of the American Navy, since early September 1941, have systematically attacked German naval forces. Thus, American destroyers, as for instance the Greer, the Kearney and the Reuben James, have opened fire on German submarines according to plan. The Secretary of the American Navy, Mr. Knox, himself confirmed that-American destroyers attacked German submarines.
Furthermore, the naval forces of the United States, under order of their Government and contrary to international law have treated and seized German merchant vessels on the high seas as enemy ships.
The German Government therefore establishes the following facts:
Although Germany on her part has strictly adhered to the rules of international law in her relations with the United States during every period of the present war, the Government of the United States from initial violations of neutrality has finally proceeded to open acts of war against Germany. The Government of the United States has thereby virtually created a state of war.
The German Government, consequently, discontinues diplomatic relations with the United States of America and declares that under these circumstances brought about byPresident Roosevelt Germany too, as from today, considers herself as being in a state of war with the United States of America.
Accept, Mr. Charge d'Affaires, the expression of my high consideration.
December 11, 1941.
Ribbentrop
On the same day, December 11, 1941, the United States responded and declared war on Nazi Germany.
Since World War 2 the United States has not formally declared war on another nation or entity.JOINT RESOLUTION Declaring That a State of War Exists Between The Government of Germany and the Government and the People of the United States and Making Provisions To Prosecute The Same
Whereas the Government of Germany has formally declared war against the Government and the people of the United States of America: Therefore be it Resolved by the Senate and House of Representatives of the United States of America in Congress assembled, That the state of war between the United States and the Government of Germany which has thus been thrust upon the United States is hereby formally declared; and the President is hereby authorized and directed to employ the entire naval and military forces of the United States and the resources of the Government to carry on war against the Government of Germany; and, to bring the conflict to a successful termination, all of the resources of the country are hereby pledged by the Congress of the United States.
(Signed) Sam Rayburn, Speaker of the House of Representatives
(Signed) H. A. Wallace, Vice President of the United States and President of the Senate
Approved December 11, 1941 3:05 PM E.S.T.
(Signed) Franklin D. Roosevelt
The “War on terror” is just one of the many undeclared wars or “conflicts” since WW2.