A total of 19 people.

That’s all it took to forever upend our world.

Even now, 23 years after 9/11 (Sept. 11, 2001), America looks dramatically different from that sunny morning when a handful of radical Islamists slammed their planes into the beating heart of our nation’s freedom, its commerce, and way of life.

We vowed then, never again.

But the lessons of the past have been forgotten under this administration, as millions stream across our open border — hundreds of them with a single goal: to destroy us.

With no regard to the danger, this White House, in which the Biden administration resides, has thrown open the gates to a stampede of evildoers.

Almost 300 people from our Terror Watch List have already been caught.

But have they been kept?

Just this week, a Pakistani national that the U.S. Border Patrol captured in November was found wandering around Los Angeles after his January release, stunning immigration officials. "Imagine how many cases like this one get through without us knowing,” one Homeland Security official told The Daily Caller anonymously.

"Who knows how many after-the-fact realizations were made after releasing someone into the country?" another agent cautioned.

"We may never know until they are encountered by law enforcement at a later date. Very well after it’s too late."

When FBI Director Christopher Wray was asked by senators in December 2023 if he saw "blinking red lights," a reference to the warning signs America missed before 9/11, he replied bluntly, "I see blinking red lights everywhere I turn."

But incredibly, Democrats — including this president — don’t care about the red lights on our southern border, only the green ones, ushering tens of thousands of unvetted foreigners into our country every day.

So while U.S. Senate Majority Leader Chuck Schumer, D-N.Y., celebrates the advancement of his Ukraine aid package — without the border reforms Americans demand — the words ring hollow.

"Today," he claimed, “we witnessed one of the most historic and consequential bills pass the Senate, a bill that so greatly impacts, not just our national security, not just the security of our allies, but also the security of western democracy as we know it."

Schumer’s right about one thing: it may prove to be consequential, but in a way that Americans never hope to experience again. What the Senate approved leaves our southern border wide open, allowing hundreds more terrorists to pour into our cities.

And setting aside the incalculable loss in human lives of 9/11, consider the toll that attack took — and is still taking — on our nation.

Modest estimates put the price tag of that horrible tragedy at $8 trillion dollars.

Around $100 billion dollars of that is the direct economic impact, but as Brown University’s Watson Institute discovered, that’s a drop in the bucket compared to what the U.S. has spent over the last 20 years in the global war on terror.

A war, incidentally, precipitated by just 19 terrorists.

There’ve been human costs, social costs, expanded Homeland Security and Defense budgets, increased veterans’ expenses, property damage, and rebuilding. Then there’s the interest we’re paying on all of it, which is — are you ready for this? — $1 trillion dollars.

It took 19 people to plunge our country into decades of financial ruin. And to what end, Heritage Foundation’s E.J. Antoni asked on "Washington Watch."

"We essentially took how many years and how many trillions of dollars to ensure that the Taliban and Afghanistan were replaced with — you guessed it — the Taliban."

All of it cost our country dearly, both tangibly and intangibly.

And, as E.J. pointed out, keeping up with war spending "gave us 40-year high inflation, a cost-of-living crisis, a banking crisis . . .  a global financial crisis, and the mortgage meltdown."

How could we possibly respond today, he wondered? "We simply couldn’t," he insisted. Just the cost of servicing our national debt is astronomical.

"I’m talking literally just paying the interest on the debt," E.J. said.

"We are quickly approaching a point in this country where the government is going to have few things it can afford besides the interest."

And just what are Democrats doing?

Shipping money we don’t have overseas and refusing to deal with an open border that’s planting countless sleeper cells on our soil.

If 19 terrorists can inflict $8 trillion dollars’ worth of damage on this country, imagine what 300 could do. According to congressional testimony, those are just the ones we’ve caught.

There’s no telling how many slipped through our hands and are now burrowed deep underground. For all we know, it could be 300 or 30,000.

As E.J. said, we’re at a tipping point.

America cannot afford another 9/11.

We need to protect our border and provide for our own national security before we attempt to help someone else.

The time has come, as it did then, for a great people to defend a great nation.

Tony Perkins is president of Family Research Council. He previously chaired the U.S. Commission on International Religious Freedom. Tony is the host of a nationally syndicated program, "Washington Watch with Tony Perkins." He is a pastor, Marine veteran, and former police officer. Read more Tony Perkins reports — Here.