All the aforementioned factors mean that the U.S. and European debt crises are complicated issues that will not be solved in a short period.

First, the public debt-to-GDP ratios of the United States and the euro zone have reached around 100 percent and 85 percent, respectively, which are unlikely to drop in the short term. This is a major problem facing the U.S. and European governments because a country's economic growth will become unsustainable if its debt-to-GDP ratio exceeds 60 percent.

Economic growth is always the ultimate solution to any country's fiscal problems. Since the United States and European countries have not found new economic growth points, it will be difficult for them to improve their fiscal situation and solve their perennial debt problems in the short term. It seems that they have to continue to borrow or raise money to pay their debts and continue to raise the debt ceiling, which will inevitably cause the debt crisis to last longer.

Second, increasing revenue and reducing expenditure are an obvious solution to the debt crisis. However, great pressure from domestic voters makes it extremely hard for the U.S. and European governments to do so. They can neither raise taxes against the will of voters to increase revenue nor easily introduce stimulus fiscal policy to promote the economic recovery to increase tax revenue.

They cannot slash the social welfare budget and at the same time are unwilling to cut the massive defense budget that helps sustain their hegemony. The debt crisis cannot be completely resolved unless Western countries' political problems are solved first.

The impact of the U.S. and European debt crisis is spreading from the economic to the political realm, which will complicate matters and make the crisis even more difficult to resolve. China should be fully aware of and well prepared for a prolonged and complex debt crisis, and avoid being dragged into the crisis, so as not to suffer heavy losses in its foreign exchange reserves.

The author is a freelance commentator for People's Daily, and a professor at the School of Economics and Management under Tongji University.