Introduction

Eighteen years after the 9/11 attacks, the terrorist threat to the United States and around the world looks very different than it did on that day when 19 foreign hijackers who had entered the United States on temporary visas killed almost 3,000 people in a matter of hours.

The jihadist terrorist threat to the United States today is relatively limited. Since the 9/11 attacks, no foreign terrorist organization has successfully directed and carried out a deadly attack inside the United States. With the territorial collapse of the Islamic State in Iraq and Syria (ISIS), the threat posed by the group has receded. It has been more than a year since the last deadly jihadist terrorist attack, and the number of terrorism-related cases in the United States has declined substantially since its peak in 2015, though there will almost certainly be an uptick in cases this year.

However, “homegrown” jihadist terrorism including that inspired by ISIS is likely to remain a threat. As this threat is not inherently tied to ISIS’ possession of territory, policymakers should not expect a substantial shift in the nature or extent of the threat of ISIS to the United States.

Rather than jihadist attacks from abroad, the most likely threat to the United States today comes from terrorists inspired by ideologies across the political spectrum, including jihadist, far-right, and idiosyncratic strains. These individuals tend to be radicalized on or via the internet, and they take advantage of the availability of weapons, particularly semi-automatic firearms, in the United States. Of particular note, in the last few years, white supremacist extremism has posed a particularly significant threat.

While the jihadist threat to the United States remains relatively limited, the United States continues to face a resilient jihadist terrorist threat across the Middle East, North Africa, and South Asia. Europe also faces a more severe jihadist threat than the United States. Yet, the United States has demonstrated its capability to deal military defeats to jihadist groups that seize territory.