The United States and the Soviet Union have to reach a certain level of income before they can declare war on the Axis. Income increases are caused by Axis actions.
The USA has a specific series of events that they can use to propel them towards war. They have to get to an income of 52 IPCs per turn before they can declare war. The USA starts with 12 IPCs per turn. These income increases are triggered by Axis aggression. Income increases are immediate (for example, if Germany captures London, the United States would immediately get the +20).
Japan builds a battleship, aircraft carrier, or cruiser: +3 IPCs per ship
Japan controls Szechwan: +3 IPCs
Axis invade any strict neutral: +5 IPCs per attack
Japan declares war on the Soviet Union: +7 IPCs
Japan captures French Indochina: +10 IPCs
European Axis declare war on the Soviet Union: +15 IPCs
Axis capture London: +20 IPCs
Japan controls New South Wales: +20 IPCs
Japan makes an unprovoked declaration of war on Britain: +25 IPCs
Axis control any North or South American territory (including Iceland and Greenland): +25 IPCs
Axis declare war on USA: Raise to 52 IPCs Income
When the USA reaches certain income levels per turn, they may do certain things:
20 IPCs: The USA may move naval units around the Pacific. They must still avoid sea zones adjacent to Japanese territories.
The USA may also move units between Pacific territories. They still must remain out of China and Japanese territories
30 IPCs: The USA may move naval units through the Panama Canal and into sz102. They may also move units into Greenland.
40 IPCs: The USA may lend-lease* to the Allies and research technology.
50 IPCs: The USA may move units into Iceland.
52 IPCs: The USA may declare war on all Axis powers and move units into China.
The Soviet Union has signed separate treaties with Germany and Japan. This places them in a unique position with regards to going to war. The Soviet Union starts with 8 IPCs, and has to get to 37. Like the USA, the Soviet Union�s income increases are triggered by Axis actions. In Europe, the Soviets receive income increases in the following situations.
Axis activate Bulgaria: +3 IPCs
Germany declares war on the United States: +3 IPCs
Japan declares war on Britain, France, or America: + 3 IPCs per declaration of war
Japan attacks Sikang, Tsinghai, or Kansu: +7 IPCs per territory
Axis activate Finland: +10 IPCs
Axis capture London: + 20 IPCs
Japan attacks any Mongolian territory: +15 IPCs per territory
If rearmament rolls push the Soviet Union to 37 IPCs, the Soviet Union may declare war on the European Axis or Japan without provocation. If the European Axis push the Soviet peacetime income to 37, then the Soviet Union may only declare war on the European Axis, not Japan. The same is true in vice versa. The other power must do one more of these actions before the Soviet Union can declare war on them. Income increases are immediate (for example, if Germany activated Bulgaria on the Non Combat Move phase of G1, the Soviet Union would immediately gain the 3 IPCs).
The Soviet Union, like the United States, has several income-determined actions:
25 IPCs: The Soviet Union may move the units in Amur, Buryatia, and Sakha into the Europe map
30 IPCs: The Soviet Union may activate Persia and Greece.
35 IPCs: The Soviet Union may invade Finland (even if it is Axis occupied), without declaring war on Germany.
IMPORTANT!!! These income increases are given immediately, once the trigger actions are taken. War can be declared as soon as your power’s income has reached wartime level (even on another power’s turn).