Now, be honest. Is that really a concern?

The states that Trump/Bannon may (and in fact proabably will) attack are hardly superpowers - Iran and North Korea.

The US military would quickly neutralize the armed forces of states like those - as proved in the Iraq "wars", Versions 1 and 2. Insurgency wars such as the ISIL campaigns, are a different matter but those hardly represent an existential threat of the type you muse about.

A situation such as you worry about would only come about if the big boys confronted each other - the US, China and Russia. And since that would be bad for business, I put that at as low a probability as even under Obama.