For Butler County residents who lived through the events of Sept. 11, 2001, and who were old enough to understand what was happening on that horrific day, this weekend’s 10th anniversary remembrances, though solemn, attach new emphasis to the chilling fact that America is not as safe as it previously was thought to be.

Even as this weekend’s memorial events are taking place, in the minds of many — if not most — people will exist questions and concealed fears about what might lie ahead.

Americans can feel a sense of thankfulness and relief that terrorist plans and attempts over the past decade have been foiled, even with terrorist mastermind Osama bin Laden having eluded his deserved justice until May of this year.

But although his al-Qaida terrorism network currently is perceived as being in disarray as a result of his death and the death of several top associates in recent months, fears remain about what al-Qaida could inflict on the United States this weekend — and beyond — even as the nation remembers what happened 10 years ago.

This weekend, President Barack Obama and former presidents will participate in ceremonies at the locations of the 2001 terrorist strikes — the site that once was home to two gigantic World Trade Center skyscrapers and at the Pentagon, the seat of America’s defense.

They’ll also participate in ceremonies at what once was a barren field in rural Somerset County near the town of Shanksville — the site of the crash of Flight 93, the commercial flight terrorists had sought to inflict a second strike on Washington.

Few could have imagined that such an attack could elude America’s intelligence capabilities and the nation’s ability to quickly quash any attack launched on the mainland.

After all, the horrific attack by Japan on Pearl Harbor on Dec. 7, 1941, was targeted at a military base on an island in the Pacific Ocean, thousands of miles from the U.S. mainland and many of the military resources that the nation had at its disposal at that time. But the attacks of Sept. 11, 2001, targeted U.S. soil, the heart of America’s economy and the seat of the nation’s government.

The wars in Afghanistan and Iraq, a fallout of what occurred on that miserable day 10 years ago, have claimed the lives of 13 soldiers who either were Butler County residents or who had ties to the county — two of them in Afghanistan and 11 in Iraq.

Although Shanksville is not close to the Nation’s Capital, what happened in the skies approaching that rural community perhaps prevented what eventually might have been a successful attack on the White House or Capitol.

Besides the method of the attacks — commercial rather than military aircraft — few Americans could have fathomed that such a small group of individuals could wreak such destruction and loss of life in such a small window of time and in such a coordinated way.

It was a scene so terrible that many schools, including here in Butler County, chose not to give students access to news reports, telecasts and radio broadcasts that day, as the nation was trying to come to grips with what was occurring and what could be coming next.

From the national perspective, the immediate and not-so-immediate impacts of Sept. 11, 2001, were many.

Commercial airline service was grounded immediately after the attacks, and remained shut down for days afterward.

Accompanying Americans’ outrage over the attacks was the birth of national unity and a spirit of patriotism not seen since World War II. If only that unity had prevailed in government throughout the past 10 years, who knows what could have been accomplished by the Congress and the executive branch.

Then there was the birth of the Department of Homeland Security, including a shake-up of the U.S. intelligence community. But amid that came fears that the federal government might be setting the stage for unnecessary erosion of Americans’ rights.

There subsequently was concern about the treatment of al-Qaida prisoners, despite the hatred many Americans harbored toward them.

But the biggest result was the birth of heightened vigilance about what might lie ahead in terms of future attacks. As part of that, increased airline security and attempts to protect utilities and other assets were beefed up.

This weekend, Americans will pray for the victims of September 2001; Butler County residents will be among those participating in those prayers. This weekend Americans will express the hope that whatever vulnerabilities still might exist in this country will never again be allowed to be exploited by those who seek to do us harm.

But as this country learned 10 years ago, America must not relax its guard. This weekend, not surprisingly, it is at a high level of alert.

With the completion of the 10th anniversary remembrances, none of the realities about possible future attacks will go away. Enemies could now be living anywhere among us, awaiting the go-ahead to strike.

It’s indeed a chilling realization, but America is not as safe from attack as it once was. The world has changed.

During this weekend’s ceremonies and remembrances, a central hope must be that the world eventually will come to its senses, although there’s not any sign of that anywhere on the horizon.