Most Americans say war in Afghanistan not worth fighting. Have we learned any lessons?

If you were born on that terrifying morning of 9/11, you could today be in military training to join that very same faraway war that started immediately after in Afghanistan.

That’s how long the United States’ longest war has been.

As he has for years, President Donald Trump says he wants to withdraw most American troops. He met with top national security advisers last weekend to discuss, among other things, “peace” talks with the Taliban who provided safe haven for Osama bin Laden to plan and train the 9/11 attackers.

An administration report on those talks is due any day.

The cover story for the withdrawal of 13,000 U.S. troops is a Taliban commitment to prohibit foreign terrorists from basing operations there and to work with the central government in Kabul, which has been excluded from talks.

But can the Taliban control lingering al Qaeda or ISIS cells, which just blew up a Kabul wedding, killing 63? And after so many years of bitter fighting can the central government coexist with the Taliban, especially if guerrillas escalate violence to disrupt Sept. 28 elections?

The Taliban will go along with the “negotiations” line for now because it offers victory with less fighting. Then come detailed talks with Kabul.

Taliban leaders claim they’ve changed since their brutal 1990s rule. The new constitution proclaims equal rights for women, who comprise a higher percentage of members (28) in the National Assembly than in the U.S. Congress.

But could a minimal U.S. presence prevent a return of harsh sharia rule, including crippling education for millions of girls, and revenge attacks on locals suspected of helping U.S. and NATO forces these past 18 bloody years?

The Institute for the Study of War reports Afghan warlords are preparing to protect and expand their turfs in an upcoming civil war with each other and the Taliban.

Let’s be clear here. The country of Afghanistan isn’t really a country by Western standards. It’s a collection of forever-feuding, feudal tribal lands.

No one in history — not Alexander the Great, not Genghis Khan, not the British, not the Russians and now not the Americans — has ever managed to conquer the entire forsaken area that’s about the size of Texas, minus Maryland.

This has been a familiar, even predictable postwar story historically when the United States gets involved militarily “helping” other countries. President Dwight D. Eisenhower, who knew war well from active commands in World War I and II, rejected involvement in Indochina when France sought help against communist guerrillas.

But his Democratic successor, John Kennedy, sent advisers to help South Vietnam combat guerrillas from North Vietnam, which had agreed to a peaceful partition.

Washington’s initial involvement was so naïve that U.S. combat advisers were barred from shooting back. By 1965, advisers totaled 23,000 and combat troops arrived, eventually totaling 550,000.

By the end of American involvement in Vietnam 10 years later, the U.S. had been torn apart by violent anti-war protests and assassinations. And almost 58,000 Americans had died while not preventing a communist takeover.

The American system of democratic government has historically been generally responsive to popular will.

And this has demonstrated to foes and allies that as tough, resilient and even generous as Americans can be, in modern times, they simply do not possess the patience or political will to finish the military efforts they so blithely undertake. They cannot outlast cunning enemies willing to sacrifice as many of their own as necessary.

Iraq was supposed to be a quick in-and-out Saddam Hussein overthrow. Of course, insurgents emerged, and the new government required stabilizing, and tribes and sects got involved. We had to surge involvement to protect the existing investment of blood and treasure, and the bog got deeper. Some 5,000 troops remain there.

By 2011, the next president, Barack Obama, was in a hurry to withdraw all U.S. troops for the 2012 election and the real war on terrorists in Afghanistan. There, he boosted U.S. troop levels at one point to 100,000.

But that left a vacuum in Iraq and civil war-torn Syria as spawning grounds for an expansionist and vicious ISIS, which Obama showed little interest in eliminating.

To his credit as promised, Trump instructed Defense Secretary James Mattis to unleash U.S. forces and destroy the ISIS caliphate, which they did in one year. Like Obama however, Trump was in a hurry to withdraw U.S. troops. It’s a bipartisan proclivity, especially the year before an attempted reelection.

Without consulting advisers, Trump late last year announced all 2,000 U.S. troops would immediately leave Syria. This was news to General Mattis, who knew ISIS would regroup in splintered bands.

The result: Mattis resigned, costing Trump his most valuable cabinet member. And those 2,000 troops are still in Syria, as Mattis would have argued.

The original U.S. presence in Afghanistan was to capture bin Laden, destroy his camps and oust the Taliban. In the ensuing 6,526 days, the United States has spent $2.4 trillion in treasure and the lives of 2,433 military men and women and another 1,143 allies.

A recent Pew Research Center poll found that after all that, nearly 6 in 10 veterans and members of the public believe the Afghan war was “not worth fighting.”

What do you think? More importantly, do you think the country and its government have learned any lasting lessons? I don’t.