We can do this safely

[T]he idea that the US can never restructure or even repudiate the national debt -- that US Treasuries must always be treated as a unique and magical "risk-free" investment -- is wildly speculative at best, preposterous at worst. Every other borrowing entity -- individuals, business firms, and governments -- has the option of renegotiating interest payments and even defaulting on loans. It is hardly an extraordinary event, even for sovereign borrowing -- that's why lenders charge a risk premium beyond the return they require to compensate for time preference. 

So says Peter G. Klein a Carl Menger Research Fellow of the Mises Institute and W. W. Caruth Chair and Professor of Entrepreneurship at Baylor University’s Hankamer School of Business.