Take China for an example. No one knows China's true military capabilities, because they're rapidly evolving and because they virtually never use them. If there's an element of surprise to be had, they have it. But that cut's both ways, because China itself doesn't have experience exercising those capabilities. The learning curve could be noticeable. Meanwhile, no one doubts the ability of the US military to execute.

Basically the only country left in the world with expeditionary capabilities is the US.

It is hard to compare this with China. Different goals and philosophies.