I remember reading that this spacecraft would not have been launched without a Russian rocket engine, and that the plutonium fuel also came from that country.
Well, to be honest, if we were to treat vendors as contributors to projects, the entire world would owe almost everything to China.
... which we do. Your point being?
We owe nothing to China considering we pay them
"Owing" something is not always about money. "The West" owes a large part of its wealth to Africa and Asia. It's a team effort, not just a business transaction.
True, but I meant a particular subset of "owing" in which you consider which parties are directly responsible for some event. Paid out vendors are usually not considered the primary parties.