9/11 at 25: The attacks that reshaped global politics

Twenty-five years after the September 11 attacks, the shockwaves of the deadliest terrorist assault in US history continue to shape American foreign policy, intelligence operations and global security.

On Sept. 11, 2001, 19 al-Qaeda operatives hijacked four passenger planes in a coordinated suicide attack. Two crashed into New York’s World Trade Center towers, another struck the Pentagon, while the fourth came down in Pennsylvania after passengers fought back. Nearly 3,000 people were killed.

Intelligence failures
The attacks followed earlier al-Qaeda strikes against US targets, including the 1998 embassy bombings in Africa and the 2000 attack on the USS Cole in Yemen.

US intelligence agencies had received fragments of information suggesting an impending threat, but failures in information-sharing between the CIA and FBI prevented critical pieces from being brought together. The 9/11 Commission later identified those shortcomings as a major institutional failure.

The war on terror
Nine days after the attacks, President George W. Bush declared a global “war on terror.” The United States invaded Afghanistan to oust the Taliban government and dismantle al-Qaeda, followed by the 2003 invasion of Iraq.

The two wars continued for more than two decades and fundamentally altered US foreign policy. The post-9/11 era also brought expanded surveillance, detention operations and counterterrorism measures worldwide.

The detention of prisoners without trial at Guantanamo Bay and allegations of abuse triggered intense debate over civil liberties and human rights.

Intelligence overhaul
Washington subsequently reorganised its intelligence architecture, seeking to prevent another breakdown in information-sharing. The National Counterterrorism Center was established, while the position of Director of National Intelligence was created to improve coordination among intelligence agencies.

The United States also deepened intelligence cooperation with allied governments.

A changing threat
The US has not experienced another attack on the scale of 9/11, but terrorism has not disappeared. According to the Center for Strategic and International Studies, the country has recorded more than 100 incidents of Islamist extremist violence over the past 25 years.

The nature of the threat has also evolved. Alongside organised militant groups, authorities now face growing concerns over lone actors, far-right extremism and online radicalisation.

At the same time, Washington’s strategic focus has increasingly shifted toward Russia and China. Security experts warn that declining attention to counterterrorism could bring budget cuts, a loss of experienced personnel and institutional complacency — potentially creating vulnerabilities reminiscent of the period before 9/11.

A quarter-century later, the central lesson remains much the same: collecting intelligence is not enough. Security depends on recognising its significance, connecting the dots and acting before warnings become catastrophe.