Stan Honda, AP
FILE - In this Oct. 11, 2001 file photo, firefighters make their way over the ruins and through clouds of smoke at the World Trade Center in New York. Many of the first responders and those who labored at the site in the months following the attacks suffer from a variety of respiratory ailments after working at the World Trade Center site. Nearly two years after President Obama signed the James Zadroga 9/11 Health and Compensation Act into law, about 60,000 responders and survivors continue to receive monitoring and treatment for their illnesses as part of the World Trade Center Health Program, one of the law’s two components. (AP Photo/Stan Honda, Pool, File

Twelve years have passed since terrorists took to the skies and caught the nation by surprise, attacking high-profile symbols of America’s economy and government and killing nearly 3,000 people whose only mistake that day was to carry on life’s normal routine.

For many, that day seems much more recent than the years would indicate.

Unlike 12 years after Pearl Harbor, the sinking of the Maine or the attack of Fort Sumter, the 9/11 attacks remain a part of daily life in America, as fresh as those gruesome images of the Twin Towers collapsing. Heightened security never has relaxed. Rather, it has turned into an enormous government enterprise that now draws fire from U.S. citizens themselves, who feel their government has turned to sharp of a spotlight on its own.

Everything from air travel to sporting events comes with visible reminders of how life changed that day. A generation now on the verge of its teen years has never known any other reality.

U.S. combat soldiers may be out of Iraq and leaving Afghanistan, but al Qaida remains an active enemy, as impossible to force into surrender as it is to eliminate through violence. On this anniversary, terrorism is the backdrop to the nation’s most vexing and immediate foreign-policy struggle as it weighs how to respond to a humanitarian crisis in Syria, where a government allied with rogue states does battle with rebels consisting of some al Qaida elements.

What seemed like a fairly simple struggle between good and evil a dozen years ago has become complicated beyond the certainty of any national consensus.

And yet on this anniversary there are hopeful signs Americans would do well to notice and ponder.

Chief among these is the visual answer to the attacks that is now on the New York City skyline. One World Trade Center rises 1,776 feet from the streets of lower Manhattan, more than 400 feet taller than the Twin Towers that were destroyed. It has been designed to withstand a bombing attack at its base. Its core is 6-feet thick in some places and designed to be resistant to fire and the type of damage that made escape impossible from the highest points of the old towers.

The building, which is scheduled to open in the spring, is an unmistakable symbol of the resilience of the American spirit — a statement that the world’s most powerful and prosperous nation intends to continue daily life, and continue its roll as a world leader in ways that include liberty and freedom, despite the best its enemies can dish out.

One other recent development is worth noting on this anniversary, as well. Through technological advances in extraction methods, the United States today is close to becoming nearly energy independent, and the North American continent is rapidly becoming the new center for the world’s oil and gas production.

While it remains to be seen whether politicians will nurture this surprising new advantage, it promises to change assumptions and rewrite geopolitical assumptions. The oil rich nations of the Middle East may soon be much less important to the United States than they have been for generations. That does not, however, reduce the threats terrorists pose to national security.

Americans must always remember that 9/11 was the work of a handful of people who wanted to create the illusion that they were a powerful and ominous world movement. While they did represent a network of like-minded terrorists that have proven frustratingly difficult to defeat, and while they maintain troubling alliances, they are a distinct minority in the world.

The key, then and now, is to secure the nation and its interests abroad without sacrificing the principles that define freedom and liberty. That is likely to remain the nation’s challenge for many years to come.