Twenty-five years after the September 11 attacks, the global impact of that day continues to shape international politics and the world order. On September 11, 2001, 19 members of the Islamist terrorist group al-Qaeda hijacked four passenger airliners, crashing two into New York’s Twin Towers, a third into the Pentagon, and a fourth into a Pennsylvania field after passengers intervened. Nearly 3,000 people were killed in the coordinated assault, which quickly drew widespread international sympathy and support for the United States.

In response to the attacks, NATO invoked its collective defense clause for the first time since its inception, demonstrating global solidarity. Russia’s then-new president, Vladimir Putin, was the first world leader to call U.S. President George W. Bush, later supporting the use of former Soviet bases in Central Asia to facilitate the U.S.-led coalition’s military campaign against Afghanistan’s Taliban regime, which harbored al-Qaeda leader Osama bin Laden.

The resilience of New York City and the United States was notable in the aftermath, with no further mass terrorist attacks on U.S. soil for more than a decade and a remarkably swift recovery in the city itself. However, the broader U.S. response has drawn significant criticism for setting the world on a more turbulent path. The decision to invade Iraq in 2003, based on claims that the country possessed weapons of mass destruction—which were never found—sparked a long and costly conflict. The invasion led to widespread sectarian violence resulting in hundreds of thousands of Iraqi deaths, damaging both regional stability and America’s global reputation. Revelations about the torture of prisoners at Abu Ghraib and other human rights abuses further undermined U.S. standing.

The two-decade-long military campaign in Afghanistan, which concluded in 2021 with the Taliban retaking control, added to these costs. The conflicts drained U.S. resources, contributing to a shift from a budget surplus to an unprecedented national debt exceeding $40 trillion, alongside significant financial crises and the economic impact of the COVID-19 pandemic.

Analysts suggest that while the decline of U.S. dominance in the 21st century may have been inevitable amid the rise of China and other global players, the post-9/11 focus on military intervention and retaliation may have distracted Washington from strategic engagement with these emerging challenges. Some argue this approach left the U.S. less prepared for shifts in global power dynamics and for dealing with an increasingly assertive Russia under Putin.

Efforts to mend America’s international image were made during Barack Obama’s presidency, though critics note a return to assertive interventionism under President Donald Trump. Trump’s administration, marked by a contentious approach to Iran and a centralization of executive power — a trend that began in the post-9/11 period — raised further concerns. Ahead of the 25th anniversary, Trump declared that the U.S. was “bigger, better, stronger than before,” a statement met with skepticism internationally given enduring doubts about America’s global role.

Overall, the legacy of 9/11 remains deeply complex, having both united and divided the international community, while influencing U.S. foreign and domestic policies for a quarter-century.