Who says the US cannot default?

Here is Barney in a previous period:

In 2003, while the ranking Democrat on the Financial Services Committee, Frank opposed a Bush administration proposal, in response to accounting scandals, for transferring oversight of Fannie Mae and Freddie Mac from Congress and the Department of Housing and Urban Development to a new agency that would be created within the Treasury Department. The proposal, supported by the head of Fannie Mae, reflected the administration's belief that Congress "neither has the tools, nor the stature" for adequate oversight. Frank stated, "These two entities...are not facing any kind of financial crisis.... The more people exaggerate these problems, the more pressure there is on these companies, the less we will see in terms of affordable housing."

Now, Zero Hedge catches Barney with this quote:

"People who own Fannie and Freddie debt are not in the same legal position [as those who own] Treasury and I don’t want them to be. ”

So, here we have it, an official attempt by senior Congress Critters to default.

Then we move on to this Bloomberg post:

China plans to nullify all guarantees local governments have provided for loans taken by their financing vehicles as concerns about credit risks on such debt surges.

So, we see that governments do default, and do so whenever convenient.