Smoke rises after two passenger jets crashed into the World Trade Center buildings in New York, September 11, 2001.(Photo: Getty)

On September 11, 2001, the whole world was shocked when 19 Al-Qaeda terrorists took control of four large passenger jets, changed their flight path, and struck targets on US soil. Nearly 3,000 people were killed, including citizens of 78 countries. More than 6,000 people were injured. Property and infrastructure damage totaled at least 10 billion USD and the total economic cost was estimated to be 3 trillion USD. The tragedy produced lasting health consequences and permanent psychological wounds, and propelled the US into its longest war in history.

Endless war

Since 2001 the global war on terror has cost the US 6.4 trillion USD, spent mainly in Afghanistan, Pakistan, Iraq, Syria, and Yemen. The costly 20-year war waged by the US and its coalition partners achieved results: it killed terrorist leader Osama Bin Laden, prevented an unknown number of terrorist attacks from occurring on American soil, weakened the terrorist group that calls itself the Islamic State (ISIS), and freed tens of millions of people from the domination of tens of thousands of terrorist fighters. In October 2019, the US announced it had killed the notorious ISIS leader Abu Bakr al-Baghdadi in a raid in northwestern Syria, marking a turning point in the war against terrorism and the greatest success of the US-led anti-terror coalition since the raid that killed Osama Bin Laden in 2011.

Names of the victims of the 9/11 terrorist attacks are engraved on the walls of two lakes that once housed the Twin Towers of the World Trade Center. (Photo: USA Today)

But analysts say the threat of terrorism is still strong. The root causes of terrorism have not been eradicated. On the contrary, they are spreading and evolving and generating more and more incidents of extremist violence around the world.

Now that the Taliban has taken control of Afghanistan and the US has completely withdrawn its troops, instability is threatening Afghanistan's path to peace. In Iraq, although the US government has announced the eradication of ISIS, the possibility of its revival has the Iraqi government worried. Not long after ISIS leader al-Baghdadi was killed, the group appointed Abdullah Qardash, one of its senior leaders in charge of Islamic affairs, as its new supreme leader. ISIS ideology is still spreading and having a great influence.

Lessons to ponder

20 years on, the American people and the world have not forgotten the horrific events of September 11 and the lessons they taught: Terrorism knows no borders. No country is immune to terrorism. Security intel is the key to stopping any terrorist plot. Political instability and conflict are breeding grounds for terrorism.

The war in Afghanistan cost the US trillions of dollars and claimed thousands of lives. In a statement on August 31, President Joe Biden announced the end of Washington's "forever war." Countering terrorism remains the US’s top global security goal, but Washington no longer prioritizes the use of military force, but will address terrorist threats around the world through its intelligence network and coordination with allies and local partners. Two decades after those horrific attacks on the US, the world is remembering the lessons of 9/11.