US on the Edge of a Catastrophe?

Newt Gingrich, former Speaker of the House of Representatives, for some reason says that the US is on the edge of catastrophe. A nuclear bomb might go off in an American city.

This is of course possible, even if I hope it will never happen, but what could the US do about it that they have not been doing since for example 9/11? Why would the risk be greater now? On top of this they have the world largest, by far, defense budget.

There is a link to the full speech by Gingrich in the link above and I recommend it. Gingrich seems to be very intelligent and knowledgeable. However, my question would be if America really can maintain the rather large security level relative the rest of the world. Have we not entered a new phase where we will see a large USA but many other large players as well?

Gingrich recommends to minimize the reaction time for catastrophes. One of the reasons that he gives is that the predicted increase in knowledge from technology and science is going to be very large in the near future. He says: we will become surprised again.

Sitting here in Sweden as an observer, I'm grateful for the resolve of the US for their own and therefore also our security. However, is it really realistic to talk about increasing the defense budget of the US under the current economic scenarios pictured for them?

Gingrich gets a question where he is asked, because of the link between security and prosperity, about the position of the US in the world. He answers that without reform he does not see the US as the leading nation in 30 years from now. He says that the greatest security threat, and Condoleezza Rice has said the same thing, is failure to provide a competitive school with science and math studies.