The Sept. 11 memorial at the tip of Manhattan is all about commemorating loss. The pools marking the footprint of the towers missing from the New York skyline and the water flowing down into the abyss below symbolizing the loss of life on that bright September morning 20 years ago.

The Calatrava transportation hub at the World Trade Center is also about tragedy and loss on 9/11. It is a kind of phoenix rising from the ashes but its spiky skeleton harks back at the way we saw Ground Zero for weeks after the terror attack, the jagged portions of the steel skin of the skyscrapers rising above the rubble.

But what about GWOT, the Global War on Terror declared by George W. Bush in the days after the terrorist attacks in New York and Washington? It was another kind of loss and it was commemorated in Kabul just days before the 20th anniversary of 9/11 by the tacit acknowledgement that America had lost that war.

Terrorism is a weapon of the weak. Unable to engage a superior military power in the field of battle — but still determined to fight — the weak resort to terrorism— to striking asymmetrically, surreptitiously and against softer targets. Warfare is determined by technology and thanks to the high-tech revolution of recent decades advanced militaries have become all but invulnerable to insurgents armed with the previous generation of weapons.

Terrorists can’t defeat their adversaries, but this isn’t their intent. What they want is to outrage, to put pressure and to goad into doing something foolish.

Thus the Italian Red Brigades were killing public officials, judges and police officers trying to force the Italian government to show its true face by declaring a military dictatorship and thus precipitating a revolution.

Advanced armies can project force over thousands of miles. They can inflict damage on their enemies without being anywhere close to them. It’s a different matter when they put boots on the ground and occupy a country. That negates their superiority and puts them on equal footing with less advanced military forces.

When the mujahideen in Afghanistan were engaging the Soviet Army they could strike at military targets — and they did it quite successfully, pushing the Soviets out less than a decade after the initial invasion.

But when Osama bin Laden turned his attention to the Americans he found that he could not inflict serious damage on the Great Satan. At Qaeda attacked the USS Cole off the coast of Yemen in October 2000, killing 17 American sailors, but that was a pinprick for the world’s largest military machine. Something far more spectacular was needed to achieve his purpose.

The attacks of 9/11 and, more specifically, the destruction of the World Trade Center, were the overpowering theater of terror. They outraged the world and stirred the kind of patriotism in the United States that is usually associated with a major war. The Bush Administration was bellicose enough in its own right, but in that climate, it came under public pressure to respond strongly. It did so by invading Afghanistan, declaring GWOT and then invading Iraq for good measure.

Bin Laden thus successfully goaded America into invading. Over 6,000 American lives were lost in Afghanistan. Another 1,000-plus NATO soldiers died there. It may not be a large number compared to losses in previous wars, but since the end result of the 20-year conflict was the restored rule by the Taliban it seems like far too many lives have been wasted.

There were other losses for the US — including reputational ones, ranging from torture and renditions during the war in terror to the ultimate American cut-and-run withdrawal. The loss of treasure has been massive — and the trillions spent abroad were the money that was not spent at home. It was also the trillions that have been added to America’s massive debt.

Add to that the security state that had been built up in the aftermath — also mostly a waste of money — and that September morning was the costliest event in world history.

The security apparatus, meanwhile, has curtailed the freedoms and the privacy of American citizens.

Equally damaging, the American involvement — including drone strikes so favored by both Barack Obama and Donald Trump, which as often as not hit weddings and other joyous events — have earned America a lasting emnity in the Muslim world. Once again al Qaeda succeeded, turning this into a civilizational conflict between the West and Islam.

And yet, enormous as 9/11 seemed at the time, I did not present an existential threat to America. The response called for police action — not a military invasion. I suspect that Ronald Reagan would have done a lot of bellicose talk but would not have committed regular troops to the operation, instead of sending special forces to inflict damage on al Qaeda.

GWOT didn’t even come close to defeating terrorism — not even militant Muslim terrorism. As the US was evacuating people from Afghanistan, a suicide bomber murdered 13 American marines and some 60 Afghans in a clear demonstration that nothing has changed.

Meanwhile, other forms of terrorism have flourished.  In America, when Timothy McVeigh blew up the Federal building in Oklahoma City, killing 168 people including 19 children, no war on right-wing militias was declared. Various armed right-wing extremists feel emboldened enough to have staged an attempted coup in Washington last Jan. 6.

Likewise, Putin’s state terrorism goes unpunished. Alexander Litvinenko was murdered in London in 2006 by Russian agents using a radioactive substance. Two other agents attempted to kill another former Soviet citizen using a banned chemical weapon. A number of mysterious deaths in the West have been credibly traced to Moscow. The attack on the Donbas was the work of Russia-based international terrorists to whom Russia openly continues to provide material support. Terrorists shot out the Malaysian passenger airliner out of the sky, murdering scores of people, including many children.

Moscow should have long ago been declared a state sponsor of terrorism, but neither Bush nor Obama, not to mention Trump, have done it.

Belarusian dictator Alexander Lukashenko feels confident enough to hijack a passenger plane and kidnap a passenger. This is the kind of piracy that the US Navy used to battle on the Barbary Coast in the 19th century.

Neither of these terrorists has faced any retribution.

Historians talk about the Long 19th Century which began with the Napoleonic Wars but ended only in 1914. The 21st century began right on schedule — in 2001, albeit only on Sept. 11th.