Or fiat currency in general. Let's not pretend modern fiat is backed by something solid. The only thing backing it these days is the promise of our grandchildren & their grandchildren being good to pay back debt, eventually.
Regularly sunk in joint exercises and simulations:
https://theaviationist.com/2015/03/05/us-aircraft-carrier-su...
https://www.eurasiantimes.com/entire-us-carrier-battle-group...