The suicide-murders and roadside bombs in Iraq and Afghanistan sicken Americans. Soon-to-be nuclear Iran seems loonier than nuclear North Korea. American debt keeps piling up in China and Japan. And we think of angry Venezuela, the Middle East and Russia every time we fill up — if we can afford to fill up.

Then listen to Al Gore on global warming. Or hear Jimmy Carter on the current president. The common denominator is American "decline."

Books by liberals assure us that our "empire" is kaput. Brace for the inevitable fate of Rome. Conservatives are just as glum. For them, we are also Romans — but the more decadent variety, eaten away from the inside.

In response, many bored Americans turn instead to the la-la land of Britney Spears and Paris Hilton.

Yet American Cassandras are old stuff. Grim Charles Lindberg in the late 1930s lectured a Depression-era America that Hitler's new order in Germany could only be appeased, never opposed.

After World War II, it wasn't long before the Soviet Union ended our short-lived status as sole nuclear superpower. And when Eastern Europe and China were lost to communism, it was proof, for many, that democratic capitalism was passi. "We will bury you," Nikita Khrushchev promised us.

After the collapse of the Soviet Empire in 1991, America proclaimed itself at the "end of history" — meaning that the spread of our style of democratic capitalism was now inevitable. Now a mere 16 years later, some are just as sure we approach our own end.

But our rivals are weaker and America is far stronger than many think.

Take oil. With oil prices at nearly $70 a barrel, Vladimir Putin, Mahmoud Ahmadinejad and Hugo Chavez seem invincible as they rally anti-American feeling.

But if we find alternate energy sources, or reduce slightly our oil hunger, we can defang all three rather quickly. None of their countries have a middle class or a culture of entrepreneurship to discover and disseminate new knowledge.

Russia and Europe are shrinking. China is an aging nation of only children. The only thing the hard-working Chinese fear more than their bankrupt communist dictatorship is getting rid of it.

True, the economies of China and India have made amazing progress. But both have rocky rendezvous ahead with all the social and cultural problems that we long ago addressed in the 20th century.

And European elites can't blame their problems — a bullying Russia, Islamic terrorists, unassimilated minorities and high unemployment — all on George Bush's swagger and accent. The recent elections of Angela Merkel in Germany and Nicolas Sarkozy in France suggest that Europe's cheap anti-Americanism may be ending, and that our practices of more open markets, lower taxes and less state control are preferrable to the European status quo.

In truth, a never-stronger America is being tested as never before. The world is watching whether we win or lose in Iraq and Afghanistan. The Middle East is either going to reform or remain an oil-rich tribal mess that endangers the entire world.

A better way to assess our chances at maintaining our preeminence is simply to ask the same questions that are the historical barometers of our nation's success or failure: Does any nation have a constitution comparable to ours? Does merit — or religion, tribe or class — mostly gauge success or failure in America? What nation is as free, stable and transparent as the U.S.?

Try becoming a fully accepted citizen of China or Japan if you were not born Chinese or Japanese. Try running for national office in India from the lower caste. Try writing a critical op-ed in Russia or hiring a brilliant female to run a mosque, university or hospital in most of the Middle East. Ask where MRI scans, Wal-Mart, iPods, the Internet or F-18s came from.

In the last 60 years, we have been warned in succession that new paradigms in racially pure Germany, the Soviet workers' paradise, Japan Inc. and now 24/7 China all were about to displace the United States. None did. All have had relative moments of amazing success — but in the end none proved as resilient, flexible and adaptable as America.

That brings us to the United States' greatest strength: radical self-critique. We Americans are worrywarts, always believing we're on the verge of extinction. And so, to "renew," "reinvent" or "save" America, we whip ourselves up about "wars" on poverty, drugs and cancer; space "races;" missile "gaps;" literacy "crusades;" and "campaigns" against litter, waste and smoking.

In other words, we nail-biters have always been paranoid that we must change and improve in order to survive. And thus we usually do — just in time.

Victor Davis Hanson is a classicist and historian at the Hoover Institution at Stanford University. Reach him at author@victorhanson.com.