Time has eased the shock of it, like moving water that rounds the edge of a sharp stone. But then you watch the videos again. You listen to the testimonies of those who barely escaped and of the loved ones of those who did not. And the emotions felt on 9/11 and the days and weeks after flood back, like your foot slipping from that dulled rock to a sharper edge just below the surface.

The terrorist attacks of Sept. 11, 2001 are among those rare events so fateful that they change the arc of history in ways we all are still coming to grips with and in ways we can never know. A generation has grown, graduated and entered the workforce that know it only as history because they were not yet born or were too young at the time to remember.

They cannot know how jarring it all was. The confusion: how could a plane crash into the World Trade Center towers on such a clear, beautiful morning? The horrible realization that this was no accident, that our nation was under attack, with passenger jets used as missiles. The profound sadness of so many innocent lives taken. The awe surrounding the heroism of the firefighters and other first responders who risked their lives, and gave their lives, to save others. The fear of what was next. The unity and resolve to confront the enemy and defeat it.

A nation would later learn of the mistakes that opened the door to the attacks. Intelligence and law enforcement agencies had not shared information which, if looked at collectively, would have warned that an attack of this nature was possible and may have led to security measures to prevent it.

In forming a Department of Homeland Security and through other initiatives, Congress sought to correct these weaknesses. And the nation has succeeded, for two decades, in the primary goal of preventing another mass-casualty terrorist attack on U.S. soil.

New York City, in particular, has made it a high priority to stop any future attacks targeting the city. Its anti-terrorism unit has international reach and has become a significant player in a global network of agencies that monitor the potential for terrorist acts.

But security officials must be held to a high standard. Suspicions must be based on evidence, not ethnicity or religion.

Troublingly, the United States has sacrificed some of its ideals in its efforts to stop terror.

Thirty-nine Muslim men remain captive at Guantanamo, 10 already cleared for release, all without trial. Some were vanished into CIA “black sites” before being sent to Guantanamo, many were subjected to interrogation methods that amounted to torture.

Guantanamo must be closed. Holding prisoners indefinitely without sufficient evidence for trial is un-American. The government must acknowledge federal court habeas petitions and let the legal system deal with these cases.

The Muslim Ban invoked by former President Trump was another moral stain on the nation, the earliest and harshest forms rejected by the U.S. Supreme Court. President Biden acted rightly in signing an executive order, on his first day in office, ending the Trump orders banning travelers from seven Muslim-majority countries from entering the United States.

We disagree, however, with Biden’s decision to follow through on Trump’s plan and remove all U.S. forces from Afghanistan. Terror networks have certainly seen the chaotic withdrawal as a victory, helping them recruit, and Afghanistan under Taliban rule could again become a haven for those plotting against the United States.

New terror threats have emerged. The Department of Homeland Security has warned of an increasing threat of attacks by “violent domestic extremists,” largely white supremacists and far-right groups fueled by “anger over Covid-19 restrictions (and) the 2020 election results.”

Cyber attacks are another growing concern, with the software of government agencies and major corporations compromised in recent cyber invasions, and companies paying ransom to get hacked equipment working again.

Most discouragingly, the burning hate that is necessary to drive an individual to become a human bomb and take innocent lives has not cooled.

While often strategically successful, U.S. drone attacks take innocent lives, with between 910 to 2,200 civilians killed, up to 450 of them children, in more than 14,000 such attacks, according to the Bureau of Investigative Journalism. The grim reality is that these strikes generate new terror soldiers to seek revenge on the U.S.

True security would come in moving past that violent cycle. But how long will that take. 100 years? 1,000 years? Ever?

For now, continued diligence must do.

The Day editorial board meets with political, business and community leaders to formulate editorial viewpoints. It is composed of President and Publisher Timothy Dwyer, Executive Editor Izaskun E. Larraneta, Owen Poole, copy editor, and Lisa McGinley, retired deputy managing editor. The board operates independently from The Day newsroom.