If you are referring to World War 2, the Japanese attack on the US base at Pearl Harbour on 7 December 1941 brought the US into the conflict.
The War has to pass through Congress and the President has to ask for it.
You did not say which war (we have had several) but I cannot recall that the US was EVER prepared for a war that we got in to- we have had to play catch up a lot.
they blew up
The Soviet Union wanted the US to open up a second front.
Military build up
it can be speeded up by a moist location.
A chemical change can be speeded up by a catalyst
Speeded up because after the war, England was in great debt so they decided to tax the colonists. These unfair taxes made the colonists want to revolt, leading up to the American Revolution.
The War has to pass through Congress and the President has to ask for it.
the reaction for them is speeded up, and enhance performance as the speeded up reactions are carried out.
The need for mass production and distribution of goods during the Civil War
A catalyst can speed up a chemical reaction.
enzymes
Kay and Cartwright
It speeded up the end of the war, thereby speeding the recovery from the wars damages. By ending the war, a difficult and costly invasion was avoided and that probably saved lives on both sides.
For the US, what sped up its entry into World War One was the German declaration that unrestricted submarine warfare was going to begin again. This meant that US ships traveling back and forth from Europe or basically anywhere would be sunk by German Submarines. This German policy basically forced the US under Woodrow Wilson to enter the war in 1917.
Increasing temperature, pressure or amount of solvent.