Axis and Allies: Playing USA
Having played Milton Bradley's Axis and Allies Classic hundreds of times over two decades, and having tried a wide variety of strategies and tactics, I offer the following wisdom for playing the United States (USA).
Having limited troops in Asia and no troops in Europe, the USA player should concentrate on a support role in the early turns, rather than being directly offensive. Use your considerable purchasing power to station bombers in England to strategically raid Germany, and send fighters to assist the defense of Russia. If Russia falls, the Axis will usually have an easy win.
If any of Germany's navy survives to your first turn, make the effort to eliminate it. Limiting Germany's options limits their effectiveness.
Another consideration for the USA is Africa. Because the UK is matched almost evenly against the German forces there, USA assistance will decide the struggle and remove Germany from the continent. If your Atlantic transport survives until your first turn, move a pair of infantry into Africa. Use them defensively, allowing Germany to destroy themselves by attacking. If you encounter a stalemate, you can divert a bomber or fighter to tip the balance. Clearing Africa limits Germany's options, ensuring their containment.
Additionally, Africa can be used as a corridor to move troops around Germany and into Asia to bolster the UK's defense against Japan's expansion there. Although this is a slow route, the timely arrival of a few tanks or infantry can turn the tide. However, do not concentrate on Africa; your main concern should be Russia's defense.
Watch for a chance to surprise attack either Western Europe or Finland-Norway. Putting troops in Germany's rear area will force Germany to redirect and deal with the threat. This can buy Russia another turn or more of survival.
Also play supportively against Japan. If UK builds an Industrial Complex in India, use your Asian infantry to help defend. Your fighter will likely be more useful defending Russia. Possibly leave 1 infantry in China so Japan cannot blitz through, but this is a situational judgement call.
Do not spend resources to grab Japanese islands in the early game. Using what you already have available, try to sneak through and grab the Philippines and the East Indies for increased income. The Philippines can also be used as an eventual fighter / bomber base to harass Japan's navy or support an invasion.
Once the UK and USA bombers are depriving Germany of enough cash per turn, the USA can turn its attention to offense. Putting ground troops into Europe is now your primary objective. Speeding Germany's collapse speeds the Ally's win. If necessary, send some ground defenders or fighters to Asia, as the UK is likely hard-pressed by Japan's forces. Replace bombers as needed to keep Germany weak.
Only after Russia is able to counterattack on its own should you consider island-hopping in the Pacific. The resources and time needed for this operation cannot be supported any earlier in the game.
These ideas are not the only course of action when playing USA, but they have worked well for me for years.