I wish the legions who, in online discussions of the US dollar (or almost anything US foreign policy/military-related), always bring up how the US dollar/economy's strength is based on the "petrodollar" (you didn't say it, but that's what you were thinking of), how the US goes to war to preserve the dollar's role as a reserve currency, how Russia/China/Saudi Arabia can cause the dollar to crash by using another currency, etc., would actually think about what they're arguing about.
No, kids, if Saudi Arabia suddenly started selling all its oil in Euros or Yen on renminbi, the US would not send the Sixth Fleet off its shore, any more than it did so to force KSA to use the US dollar to price its wares in the first place. Saudis (and Russians, and Chinese, and everyone else) use the US dollar because they find that a) using it is more convenient than another hard currency like the Swiss franc or British pound, and b) no one else wants riyals, rubles, or renminbi.