Here's a graph of both our net external debt and our trade deficit, graphed against our GDP, which you can safely treat as equivalent to GNP:
Our debt is clearly "skyrocketing", and it is a growing problem; the question is really how serious is it? There are economists that do indeed go with the panglossian school, such as Federal Reserve Governor Bernanke and Larry Kudlow; some who are concerned, such as Federal Reserve Governor Gramlich (the source of this graph); some who are quite concerned, such as Paul Craig Roberts.
Going by objective criteria such as those published by the World Bank, I believe that we are in the worrisome stage where we are likely to start seeing serious talk about cutting our AAA credit rating, much as was done to Japan because of their very large fiscal debt -- and Japan is our primary lender. My profile has more about this subject.
I would very like to see us adopt trade policies that do not indebt ourselves to pay for manufactured goods and for services. Indebting ourselves to acquire assets, that can indeed be good business; indebting yourself to consume a Mexican lettuce or fire a Chinese firecracker is clearly not.