It was a peaceful morning on the United States East Coast. Nobody anticipated the calamity coming their way from the otherwise cloudless, beautiful sky. It was Sept 11, 2001.

From 8:46 am to 9:37 am, three of four hijacked passenger planes, bound for West Coast cities of Los Angeles and San Francisco from three East Coast airports, were crashed into the twin towers of the World Trade Center in New York and the Pentagon near Washington DC.

The images of the twin towers collapsing were as shocking as they were transformative, irrevocably changing the United States, and the world. Like all incidents of historic proportions, the 9/11 attacks have been at once unifying and divisive, inside the US and throughout the international community.

When the US and the world at large look back on the 20th anniversary of the bloodshed, different people will be remembering it in different ways, and taking different lessons from it.

With the less than handsome finale of the US war in Afghanistan sinking his approval ratings, President Joe Biden will have to strike a tough note against terror when he visits the sites of the attacks on Saturday, both to make up for the perceived weakness in his handling of the Afghan drawdown and to defend the global US strategic contraction he is presiding over. Nor will former president George W. Bush, who personally launched the US "war on terror", or his successor Barack Obama, be willing to concede US failure in their personal remarks commemorating the anniversary.

Bush declared that it was "mission accomplished" for the US in Iraq on May 1, 2003. Obama made the same statement about the US war in Afghanistan on Jan 11, 2013. And Biden repeated Obama's words upon the departure of US troops from Kabul.

But neither the "war on terror", nor follow-up military operations spanning the past two decades have brought the degree of success the US leaders have touted. The US invasion of Iraq turned out to have little, if anything, to do with terrorism. The war in Afghanistan, except for driving al-Qaida underground and killing Osama bin Laden, has seen the resurgence of the Taliban, and ended with a deadly terrorist attack by Islamic State-Khorasan, an affiliate of the IS as dangerous as al-Qaida.

The Taliban have promised they won't allow terrorists to use their territory to launch attacks against the US. But obviously they don't have control over the IS-K. And of course, Afghanistan is not the only place hosting international terrorists.

While the terrorist attack at Kabul airport was a bloody reminder that anti-US terrorists remain alive and well, the January onslaught on the US Capitol, defined by US Department of Homeland Security as domestic terrorism, has sounded the alert against the rise of a homegrown variety.

One core lesson from such incidents is that force is not the solution to terrorism, overseas or at home. What's worse, the fight against terrorism may even backfire to damage global anti-terrorism cooperation if it is used as a political tool with double standard to safeguard the US hegemony by attempting to set up different anti-terrorism groups based on ideology and Cold War mentality.