If we were to get in to a war against a first world country, how exactly would the American perspective of warfare change?

I mean it as in tank vs tank, jet vs jet, and naval warship against naval warship. For the sake of the discussion, neither country uses Nuclear Warfare so as to keep foreign relations from withering away completely.

I ask this because as far as I know, today's wars are mostly a first world country fighting against another which doesn't have a modern military to support it. We're fighting against enemies that don't have the resources to build tanks or jet aircraft, or to wage naval war at all.

If the USA and Britain were to get in a war for some impossible reason, with the outcome being that Naval servicemen dying aboard sinking ships, aircraft being shot out of the sky, and tanks being blown up by other tanks, how would the American media react? It's a front page story when a serviceman dies from a bomb, but how would it be if the USS Ronald Reagan were to be sunk?

I ask this mainly because I've thought about joining the Navy several times (Ideally as a pilot, but I have alternative aspirations), and it strikes me that today's service seems to be traveling the world first, and a job second, instead of "Defending your home country." I'd like to know how it would apply to all servicemen. IE, how would you react to having an enemy having their rifle taken away, but given a tank instead?

Tl;dr

What would it be like if we were to have something along the lines of WWI or WWII, but with modern weaponry on the two opposing forces as opposed to the urban warfare we so commonly see today?