Lower oil prices make already unstable U.S. suppliers more volatile. Economic weakness in Mexico empowers drug cartels on the southern border. China faces more domestic unrest, leading to government crackdowns. Increased protectionism stifles recovery at home and abroad, and global perception of America's power is harmed as the nation's economy founders.

Add to those scenarios a U.S. military viewed as weak from scaled-back defense spending to cut costs, and it's easy to see how the global financial crisis threatens U.S. national security, according to testimony prepared for a House panel Wednesday.

"The most important effect of the financial crisis and subsequent recession may be the least tangible — a serious worldwide erosion of confidence in American competence, a confidence which previously almost carried a sense of invincibility," Richard Cooper, an international economist at Harvard University, said in written testimony for the House Armed Services Committee.

U.S. officials recently have warned that the nation's recession and global financial crisis were top security concerns. Director of National Intelligence Dennis Blair has said the economic weakness could lead to political instability in many developing nations.

The House panel also is concerned about how the government is devoting money to handle the crisis. President Barack Obama has proposed a 4 percent increase in defense spending to $534 billion during the next fiscal year.