I was skimming through the Worlds of Android book and in particular the Worlds War where it mentioned the wars on Luna and Mars became a battle for National interests.

My question is if the US owns the beanstalk and the beanstalk is the most efficient way of travel by far, how was any other nation able to get a sizable military presence (troops and equipment) into the hotspots to be able to come close to challenging the US military presence there?

I doubt even the Weyland Corporation is corrupt enough to let foreign military hardware and troops travel through the beanstalk. Even if it was the US government isn't going to let them travel over US soil especially for the sole purpose of fighting US forces off world.

As I said I only skimmed and don't have a good grasp of the lore or the science behind it so there's heaps I could have missed that explains this.

I believe the fighting off world was mostly with people already on the Moon and Mars. There were different colonies and companies with different national allegiances. For example Horizon is a Chinese colony on Mars. Once the SXC is mobilized to the Moon it sounds like they shattered the resistance though. Mars was a more protracted conflict. Even the US has a logistical issue sending a sizable force to Mars.

In addition to the Beanstalk there is still the dropships which are more costly, but seem in wide use considering their description. So it is possible for a nation to mobilize troops without using the Beanstalk. Note that means it would be more costly for them to wage war than compared to the US. At the same time countries like Russia seems to have bankrupted itself during the war while the US didn't and the US fielded far superior forces. So that all adds up to me. Only China gets a note in the book about a substantial force deployed to the Moon to retake their colony. So it's possible China did use the Beanstalk to transport troops. At the same time China is also theorized to be secretly working with the US to regain control of their colonies from the natives... so there is that. After the Treaty of Heinlein the Beanstalk is suppose to be controlled by a multinational organization the SEA (though they say Weyland and the US still get preferential treatment).

Thanks Phillos, that makes a lot of sense and does add up that the US were able to largely dominate the war after the deployment of SXC due to their superior ability to get (relatively) larger numbers of troops and resources to the battle fronts more efficiently. I had skimmed past or forgotten about the dropships, which also explain how other factions were able to stay in the war but were still at a disadvantage.