My posting has generated quite a stir, I will try to explain the reasons behind my statement.
There are several matters that are badly out of kilt in the US, I will list them in no particular order: huge and increasing federal trade deficit; huge federal borrowing; huge personal borrowing; real estate bubble; hedge fund speculation on such a scale that it has a larger influence on the stock market that the actual state of the economy.
Add to this the external factors: the two largest oil producers in the world are Saudi Arabia and Iran; China's economic power is transformed into political power, but they are still a communist dictatorship; China, India, Latin America and Eastern Europe are taking away all manufacturing jobs in the western world.
The destabilisation of some of the above countries or US internal factors could trigger a chain reaction that would bring the whole world into recession. Some of the possible scenarious: Nuclear attack by Iran. Collapse of the communist regime in China or War between China and USA; Islamic revolution in Saudi Arabia; Massive and multiple attacks against the western countries by islamic fundamentalists, etc.
Most of the above is the stuff of fiction, they are more an intellectual excercise than reasonable scenarious, but if any of them were to happen, the consequences would be hard to anticipate. Honestly, before 9/11, who would have believed that islamic fundamentalists would attack the Pentagon from the air?
The above are just my musings and they portray a one sided view, the world is never so black and white, however, can you imagine what would have happened if the USSR would have launched nuclear missiles from Cuba at the time of the Cuban Missile Crisis?