No, they aren't. 

The fed could dissappear tomorrow and the treasury could still issue debt.

It would merely have to be paid for by the savings of individuals, companies, funds, banks, etc..  

This is 100% possible without fractional reserve banking and could still be the case on a bitcoin standard in fact.

The fed can print at will within reason, but also has to handle inflation as part of their law, so they can't in reality.  They certainly could print it, and it doesn't matter. If it stays at the fed, it has zero affect on the global economy. Without the velocity and moving into private hands, it would be just a number.