Perhaps the most important lesson from Afghanistan can be discovered by looking at what happened in Afghanistan as being representative of a much larger pattern in US foreign policies.
As a Canadian, one thing that has always amazed me is how easily and how often the US decides other countries are enemies of the United States, worthy of either economic warfare (sanctions), or a military response.
Consider the initial US decision to invade Afghanistan. After 9/11, The US Government demanded that the Taliban government immediately turn over Osama Bin Laden to US officials. The Taliban expressed a willingness to do so, but only after being presented with evidence of Osama Bin Laden's guilt - which would have been the normal due process under international law. That answer was unsatisfactory to the U.S. Government, which immediately invaded.
One could say that the Taliban were just stalling for time, that they had no intentions of turning over Osama Bin Laden. If that were the case, it was easy enough for the US to call their bluff by turning over the evidence it had, and again demanding Osama Bin Laden be turned over to US custody. All that would have been lost was a week or two, and it might have avoided a war.
Immediately rushing off to war did not further the goal of bringing Osama Bin Laden to justice. He was never brought to trial, and was finally killed only years later. The war in Afghanistan ended up costing about as many lives as a second 9/11, and something on the order of two trillion dollars of taxpayer money. In retrospect, the American decision to not give due process a chance to bring Bin Laden into American custody was a very expensive one.
Something similar happened in Iraq. America was initially ready to rush into war with Iraq as part of a headlong rush to seek vengeance for 9/11. When various observers pointed out that Saddam Hussein had made no secret of his long-standing hatred for Al Qaeda, the U.S. Government quickly shifted its argument to claiming that Iraq possessed dangerous "weapons of mass destruction."
Once again, rushing into war proved very expensive. So far, more than 4,400 US military personnel have died in Iraq, with almost 32,000 injured. Cost estimates for that war go as high as 3,000 billion dollars.
After the fact, evidence emerged that much of the intelligence information on which the U.S. went to war was invented speculation by Iraqi dissidents wanting to manipulate the U.S. into ridding their country of Saddam Hussein. Oops.
I would like to suggest that this American tendency to create as many enemies as possible has two unfortunate outcomes. The first bad outcome is that it tends to create safe havens for terrorists.
An after-affect of the US taking out Libyan strongman Muammar Gaddafi is that Libya has become a failed state. It has become a safe haven for terrorists. So has Syria, and to a lesser state Iraq.
The U.S Government is currently working hard to undermine and sabotage the new Taliban Government in Kabul. What happens if they succeed, and Afghanistan degenerates into the chaos of civil war? Afghanistan will once again become a paradise for terrorists. Is that what America wants?
There's a second bad outcome of America's propensity to create enemies. One after another, America has been driving its enemies straight into China's arms. First it was Russia. Then Cuba and Nicaragua. Then Iran and Syria. Then North Korea and Venezuela.
As a Canadian, this mystifies me. Most Americans I talk to seem pretty well grounded in reality. Yet their Government displays an out-of control paranoia that gratuitously manufactures enemies.
What do I mean by gratuitous enemies? How likely is it that Venezuela or Nicaragua will try to mount an armed invasion of America any time in the foreseeable future? I would suggest, for anyone at all grounded in reality, the odds of either nation attacking America any time soon are less than one in a million. These are gratuitous, manufactured enemies. That doesn't mean America can create a large numbers of enemies without there being consequences.
Many in the US are worried that the US will one day find itself at war with China. That seriously understates the risk. The real risk is that the US will find itself at war with a grand coalition of countries the US has driven into becoming China's allies.
Again, though the US experience in Afghanistan has ended very badly, that does not mean that it could not get worse. If the US drives the new Taliban Government of Afghanistan into China's orbit, that would have three important consequences. First, China would be the main beneficiary of developing the trillions of dollars of mineral wealth under Afghan soils. Second, China will be able to add a important link to its Belt and Road Initiative, further cementing its links with Iran. And finally, China will be able to add Afghanistan to the list of coalition partners it would have in any war with the United States.
This is the most important lesson I see for the United States in reflecting on what has happened in Afghanistan. The USA needs to be more restrained and judicious in deciding who are America's enemies. Otherwise, the USA will continue to create new havens for terrorists. Even worse, the USA will continue to spend trillions of dollars to create new economic and military coalition partners for China.
World War 3 will be all the country's VS America and Canada. I'm not excited for that one.... Especially considering China will probably make some sort of laser gun and make a portable forcefield. Might be time to move to China!