I'm neither an accountant nor a lawyer, but my opinion is that you cannot be taxed unless you realize a profit, in which case it would be taxed as a capital gain (if you're dumb enough to report it). And I would opine also that it matters not whether you sell it abroad or in the USA; however, the country where you sell it might want to tax you, either on the profit or via a sales tax.
I recall touring NE Canada in 1971 towing a large travel trailer, and having to fill out a lot of paperwork on entering the country. On leaving we should, apparently, have completed the rest of the paperwork but nobody asked me anything when we crossed over at Niagara Falls. Some weeks later I received a letter from some Canadian government revenue department demanding proof that we had re-exported the car and trailer and not sold it in their country. They suggested that I return to the "port of exit" and show the car and trailer.
Yep, sure. I'm going to make a 500-mile round trip to satisfy some bureaucrat. And the trailer was rented in any case. I got some more letters for the next year, and then they petered out. I have them somewhere with the one I received from the Mounties - big impressive coat of arms etc. - threatening to "arrest you on sight" if I came back to Canada because of a dozen or so ignored parking tickets. These people take life so seriously!