Before the September 11 terrorist attacks 20 years ago, not many Americans knew about Osama Bin Laden and Al-Qaeda while the self-proclaimed Islamic State (IS) organisation had not yet emerged.
The great collapse of New York’s Twin Towers led to a dramatic shift in Americans' attitudes and concerns about safety and threats within the US.
Under pressure from public opinion after the terrorist attacks, the US Congress passed a series of new acts and laws, such as the Authorization for Use of Military Force (AUMF), which permits the President to carry out attacks on terrorist threats, and the Patriot Act, which gives more oversight to federal agencies to combat terrorism and protect national security.
In October 2001, President George W. Bush declared the war on terror in Afghanistan, which Washington accused of providing sanctuary for terrorist leader Osama Bin Laden. In March 2003, Washington expanded its military presence in the Middle East, attacked the terrorist organisation Al-Qaeda in Iraq, and plunged itself into a lengthy war involvement in Afghanistan.
Over the past two decades, the US military has also expanded its anti-terrorism front throughout the regions, confronting many organisations, such as Hezbollah in Lebanon and Palestine, and IS in Syria, Libya and Iraq. Osama Bin Laden was killed in Pakistan in May 2011. But so far, the war on terror triggered by Washington in the anger of Americans after the September 11 has not yet stopped.
The 20-year war in Afghanistan has cost the US trillions of dollars and claimed the lives of thousands of soldiers. In a speech on August 31, President Biden announced the end of the war to focus resources on more prominent issues facing the US.
Although countering terrorism remains a top international security goal of the US, Washington no longer prioritises the use of military force, but will address terrorist threats around the world through its intelligence and communications network, its coordination with allies, and local partners.