Ten years after Sept. 11, 2001, Americans understandably ask, "Are we safer today than a decade ago?"

Unfortunately, there is no mathematical formula to answer that question. The only honest, realistic response is mixed: In some important ways we are safer, but in many others we are not. We have taken significant steps to become safer, but not enough. To be equally honest and realistic looking ahead, we must admit that the United States unquestionably faces a dangerous and uncertain future.

The first and most important factor in evaluating our national security is the attitude of the American people. Throughout history, an attack like 9/11 would have sent some countries scurrying for cover, and their leaderships into appeasement mode.

That is not how we reacted. Instead, we retaliated against the terrorists, destroying the Taliban-al Qaeda regime in Afghanistan. Faced with Iraq's repeated misconduct and violations of Security Council resolutions, we concluded the unfinished business of the 1990-91 Persian Gulf War, overthrowing Saddam Hussein. At home, we increased border and airport security, and overall alertness.

Unfortunately, we are beginning to forget the lessons so painfully learned on 9/11. Too many ignore subsequent failed or partially successful attacks (such as the Times Square bomber and the Fort Hood shootings), and the continuing danger they demonstrate. We are prematurely withdrawing from Iraq and downsizing in Afghanistan, and we hesitate even to discuss the "global war on terror" for fear of offending someone.

The unwillingness of too many Americans--and worse, too many of our purported leaders--to shoulder our responsibilities relates directly to the second factor: the international threat levels, which rise and fall for many reasons completely unrelated to America. Contrary to the view of those Jeane Kirkpatrick called the "blame America first" crowd, global threats do not arise only in reaction to U.S. policies.

Even after Osama bin Laden's well-deserved death, international terrorism remains a mortally serious danger. Al Qaeda has metastasized and spread in the Arabian Peninsula, North Africa and elsewhere, and new terrorist groups have arisen. The peril has expanded and diversified. It never centered on one man or one group in the past, and does not today.

"Unfortunately, we are beginning to forget the lessons so painfully learned on 9/11." -- John Bolton

And the international risks America faces extend well beyond terrorism. The proliferation of weapons of mass destruction--nuclear, chemical and biological--and the ballistic and cruise missile systems needed to deliver them continues essentially unimpeded in Iran, North Korea, Pakistan and perhaps elsewhere.

Larger strategic challenges also abound. China's growing economy enables it to make assertive, even aggressive territorial claims in nearby seas; expand and upgrade its nuclear and missile forces; modernize its conventional assets; develop a blue-water naval capability; and plan asymmetrical warfare programs to challenge U.S. naval dominance in the Pacific for the first time since 1945. Russia, too, based on its burgeoning oil revenues, is modernizing its ballistic missiles and nuclear warheads, and vigorously attempting to re-establish hegemony over independent countries formerly part of the Soviet Union, and in Eastern Europe.

America's response to these numerous threats has been feeble at best. Much more is required to protect America than airport screening procedures, which many Americans today unwisely regard as nuisances rather than necessary protections. (Perhaps they will be mere nuisances one day, but not yet.)

Currently, we are quite rightly focused on getting our economy back into shape, although success is seemingly elusive. But we must remember that there has always been an inextricable link between a strong economy and strong national defense. We cannot have adequate national security without a prosperous economy, and we cannot sustain that economy if we are unable to protect ourselves, our interests and our friends abroad.

Today, however, we are in considerable danger of ignoring that linkage and ignoring the manifold threats that still exist, instead hoping we can just press a "reset" button to make the threats disappear. In trying to solve the serious problem of massive federal government overspending, we are risking huge, indiscriminate cuts to our defense budget. Doing so would leave America with a hollowed-out military incapable of providing comprehensive global protection.

While concerns about our continuing safety are very much with us 10 years after 9/11, Americans have never been known to whistle past the graveyard. We should insist on having the historical willingness President John Kennedy invoked in his inaugural address, to "pay any price, bear any burden, meet any hardship" to keep our country free and secure. That is the real lesson of 9/11.

John R. Bolton is a senior fellow at AEI.