United States Strategies

Characteristics
Being the most powerful nation by far, you're intended to win with few other nations. However, at higher difficulties, winning can be hard, given that most nations can reach American and Canadian territories through the North Pole, so it's advisable to expand and build at least a couple cruisers in every northern territory, while you use the southern ones to research. Even through Brazil may be a pain at the start, its limited technology will make it less than a threat if you pay attention for cruisers and IRBMs. Russia, China and Western Europe are major threats, though you'll still have the upper hand at the beginning, having more territory than W. Europe and more tech than Russia.

Use Florida, Texas or California to expand south early while using the northern states to expand into Canada. Aim for Alaska and Greenland early on, otherwise Russia and Western Europe will have territories close on you. Remember to have at least a couple cruisers in most of the northeastern counties, as most of the threats will come by this way. You may want to focus on researching the Trident IRBM Rocket, since it will upgrade the already unlocked IRBM Rocket, and making advantage of it since most of the enemy nations are inside the range of it, making it more suitable than the long-range ICBM. If Brazil is absent, expand south and then occupy Africa. Most of the First Strikes will aim for Africa, since it's closer (however it isn't a global rule and nations may aim for your capital instead). Try to maintain your territories and you'll probably be good.

Since USA starts with the Satellite Recon Optics (which remove the fog), the IRBM Medium Rocket and the Enhanced Cruise Missile, you may start off aggressively, trying to finish off smaller nations right off as soon as possible to reduce both the number of enemies and the effect of multiple, simultaneous First Strikes in your territories. However, it's risky, since it may prompt other nations to attack you back while your counties are in cooldown after a launch.