History is loaded with dates that changed our country forever: The signing of our Declaration of Independence on July 4, 1776. The start of our civil war on April 12, 1861. The attack on Pearl Harbor on Dec. 7, 1941.

Add Sept. 11, 2001, to that list. Nearly a year has passed since that day when thousands died, mighty towers fell and part of the Pentagon became an inferno. We are just beginning to grasp how our lives have changed.

I'll never forget that day. I was conducting a discussion on free trade in one of our conference rooms when I heard that a plane had hit the Pentagon just minutes after two other planes had slammed into the World Trade Center in New York.

"Oh, God," I thought as I saw black smoke rising over Washington through our office windows. The unthinkable had become undeniable: America was under attack.

Suddenly, the issues that government was concerned with, such as health-care reform and education, seemed trivial. Meanwhile, other issues, such as whether we should field a missile-defense system, became more crucial than ever.

America has re-evaluated its resources and refocused its abilities to define a new agenda for the world. My Heritage Foundation colleagues did the same and began studying homeland security and terrorism more closely-two issues I never thought would take center stage when I became Heritage's president in 1977. Some elements of that new agenda include:

Defense. We didn't respond to international terrorism as if it were a crime by convening grand juries and issuing subpoenas. We selected a major target, Afghanistan, and removed a major sponsor of terrorists, the Taliban. Now there is serious talk of conducting a similar mission with Iraq, another major exporter of terrorism.

There are reports that Iraq is preparing for the worst and, judging by what we accomplished in Afghanistan, it should. For one thing, we didn't fight the Taliban with one hand tied behind our back, as we often fought the communists in Vietnam. We hit Afghanistan with nearly everything we had and fought them in every way we knew how. We went after terrorists financially by freezing funds of so-called Islamic "charity" groups. We went after them diplomatically by building coalitions against terror. And militarily, we not only used the latest in high-tech weaponry, we also delved into our past to better kill the enemy. For example, many units of the U.S. Special Forces hunted down Al Qaeda and Taliban fighters not in tanks or trucks, but on horseback.

This all-out approach to fighting terrorism was a major change for the United States. In the past, we and other nations "outlawed" hijackings, hostage taking and other activities. We brought terrorists to trial and even convicted them. Yet on Sept. 11, our enemies showed the bankruptcy of this approach. So the United States reverted to the wiser tactics of the past.

We also accelerated our plans to develop a missile defense. We did that in the past year by rejecting such outdated frameworks as the 1972 Anti-Ballistic Missile (ABM) Treaty. (flash presentation)

Some said that missile defense should be further down the list of priorities in fighting terrorism, but think about it: The death and destruction we witnessed almost a year ago were the result of commercial airliners, loaded with combustible jet fuel, crashing into their targets at high speeds-much like a missile. It's only a matter of time before a real missile, possibly with nuclear or chemical weapons, is aimed at America.

Sound far-fetched? No more so than the idea of jet planes slamming into the World Trade Center and the Pentagon. Like it or not, what was once unimaginable has become all too real. We can't underestimate the capabilities and craziness of those who wish us harm. We learned the hard way that defending America means closing down avenues of attack that once would have seemed the stuff of a Tom Clancy thriller.

Economy. Unfortunately, some attitudes haven't changed much after Sept. 11. For example, I thought America was past the point where you just throw large sacks of money at a problem. But apparently that's not the case, as the government threw billions at the airline industry this past winter, which was ailing financially before the attack.

Later, in the name of national security, President Bush and Congress created a farm subsidy law that benefits wealthy "agribusiness" and "farmers" such as basketball star Scottie Pippen and media mogul Ted Turner-not the small, family farmers who might actually need help.

The urge for government to support the airline and agriculture industry might have felt like the right thing to do. But one of America's greatest strengths is its economy, which is strong in large part because government more or less takes a "hands-off" approach toward it. As the philosopher Friedrich Hayek noted 57 years ago in the classic "Road to Serfdom," when government takes a role in planning the economy in war, it likely will want to plan the economy in peace-and that means less freedom for everyone.

Energy. Before Sept. 11, President Bush's energy plan seemed to be fading like an old light bulb. The rolling blackouts predicted for California two summers ago never happened and the debate about drilling in the Arctic National Wildlife Refuge (ANWR) almost slowed the plan to a halt.

But now, more than ever, we need a national energy policy that encourages more U.S. oil production because we can see how closely it's linked to national defense. America currently imports about 60 percent of its oil from OPEC nations that aren't always friendly to us. Back in the early 1970s, an embargo by OPEC nations nearly crippled the nation-and we were importing a mere 40 percent of our oil back then.

We can't afford to let that happen again. But Congress has been stalling on the president's energy plan for months now, so history might just repeat itself.

Security. One of the more obvious changes after Sept. 11 was the attention given to improving security in America. At U.S. airports, for example, security is tighter than it ever was before-right down to inspecting passengers' shoes for bombs.

But some of the measures done in the name of security have bordered on the ridiculous. The American press often carries stories about people who were forced to give up such innocent items as nail clippers in the name of security. Even former Vice President Al Gore was stopped by airport security twice on a recent trip. Although some measures were long overdue, others need to be rethought and applied more wisely.

Society. One of the biggest changes in America that occurred after Sept. 11 was life itself. People bought more cell phones to call loved ones in an emergency. Some designed "safe" rooms in their homes in case of another attack. New words and phrases cropped up in everyday language such as "homeland security," "daisy cutter" and "first responder" Before Sept. 11, few Americans even knew what "Al Qaeda" meant in Arabic, let alone what it was. (It means "the base.")

But not all the changes that happened among Americans were negative. A renewed sense of patriotism swept the country as thousands volunteered to serve their country in the military, intelligence agencies and elsewhere. The American flag was no longer reserved for special holidays as the Fourth of July; displaying it became a full-time commitment. And singing the national anthem at baseball games and other sporting events went from being a ritual to a moment of true pride.

America will never be the same. There are many areas where we have moved ahead to promote our national interest, which is to preserve freedom and prosperity around the world. And someday-probably not as far off as we think right now-those goals will be in the national interest of every country on Earth.

When that happens, mark the date. It will be the biggest change of all.

Edwin J. Feulner, Ph.D. is president of The Heritage Foundation, a Washington-based public policy institute.