The United States of America's Capacity To Actually Sustain a Multi-Front War, Told In Two Graphics

For the moment: the weapons, the technology, the so-called allies. Let's look are the numbers and the locations.

First, here's the largest armies in the world:

Next. let's look at breakdown of US military bases, so we know how many troops are where:

Just going by the numbers as a lay person I can say that the United States does not have enough personnel to have a sustained conflict with China, Iran and Russia. It would take too long to move troops around, and there's not enough to fight abroad and protect at home. 

If you factor in technology, all three of those countries have the tech to match or exceed what the US has. Allies? Their number, while certainly appreciated, are negligible

Lastly, there's experience: China may be rusty, but Iran has been living in an area of constant tension and Russia has the most experience army in terms of modern warfare (#2 would be the dwindling forces of Ukraine). America, meanwhile has not fought a real war since WWII; everything between then and now have been militias, rouge nations and terror states with no solid infrastructure, economy or citizenship...three things that can motivate a country to fight. 

The United States does not need to use acts of violence and war against these countries. But a combination of imperial arrogance and capitalistic selfishness is preventing the leaders from embracing a multi-polar world where one country doesn't call all the shots. 

.