Thanks, this is the right answer. It's actually in the 14th Amendment:
Section 4. The validity of the public debt of the United States, authorized by law, including debts incurred for payment of pensions and bounties for services in suppressing insurrection or rebellion, shall not be questioned.
The U.S. Constitution actually requires us to repay national debts.
Debts can be renegotiated though. That's right up our President's alley.
Thanks, this is the right answer. It's actually in the 14th Amendment: