Domestic terror is low now.

Yet despite this toxic stew of anger and threats, actual terrorism — politically motivated violence against noncombatants that seeks a broad psychological effect — was low in 2021.  reveal there were zero — yes, zero — successful far-right, left-wing or Islamist militant mass terrorist attacks in the United States so far this year. It’s a remarkable statistic and one not reached at any time after 9/11, 20 years in which jihadism and white supremacist violence, in particular, vied to claim the most American lives. The lone lethal attack that might even be considered terroristic involved a misogynistic man who killed eight workers at massage parlors and spas in Atlanta due to a self-proclaimed “sex addiction.” A depressing number of mass shootings occurred in 2021, but despite being murderous they are not terrorism as they did not involve a political motive.

[]

Islamist militant violence in the homeland has been on the decline for years: 2020 also saw no Islamist militant attacks in the United States; the most recent strike was the December 2019 shooting at Naval Air Station Pensacola, Fla., in which three sailors died. The shooter, a Saudi air force officer in the United States for training, had ties to al-Qaeda’s Yemen branch. The last mass casualty Islamist militant attack was in 2016, when an Islamic State-inspired shooter killed 49 people at the Pulse nightclub in Orlando.

The 2021 dip in right-wing attacks is more surprising. In 2018, Robert Bowers shot 11 worshipers at a Pittsburgh synagogue, the worst act of antisemitic violence in U.S. history. 2019 saw 22 people killed at an El Paso Walmart, with the shooter targeting local Hispanics in an effort to stop foreign “.” Those years also saw smaller attacks, as did 2020, when a member of the anti-government “Boogaloo” movement .

Given the turmoil of our time, and this recent history of terrorism, why did 2021 see so few terrorist attacks even as threats of violence seemed everywhere?

For Islamist militants, the answer is the most straightforward. Massive attacks such as al-Qaeda’s 9/11 or the 2015 Islamic State attacks in Paris depended heavily on skilled operatives carrying out orders from a dedicated, well-resourced group: The attacks took time, money and organization. Other Islamist militant attacks depended on inspiring locals, like the Pulse nightclub shooter, to take up arms on their own.

The United States and its allies, however, have slowly ground these organizations down. The al-Qaeda core has been a prime target, losing its working-level operatives, as well as its senior leaders, in drone strikes or through arrests from . The core has not carried out a major attack on the West for over a decade, and some of its affiliates like the Yemen branch that facilitated the Pensacola attack are in disarray. At home, the FBI is far more aggressive () in targeting potential Islamist militant terrorists than it was before 9/11, while the American Muslim community  to stop the small number of dangerous individuals in their midst. Bottom-up, inspired attacks remain a concern, but the decline of both the Islamic State and al-Qaeda leaves them less able to capture the imaginations of excitable potential supporters.

None of these factors are unique to 2021. They represent a culmination of policies from different administrations and learning by counterterrorism officials. No single one of these measures stops terrorism by itself, and, despite two years of calm, at least some future attacks remain likely — but the combination is potent in keeping the U.S. homeland largely safe.

[]

Right-wing terrorism is another matter. The Trump administration did not prioritize it, and , hindering law enforcement efforts to anticipate and disrupt it. Many of the topics right-wing terrorist movements embrace — suspicion of the federal government, opposition to immigration and hostility toward religious and racial minorities — are part of mainstream political debates already. With covid and broader polarization, anti-government sentiment has grown. Add to that a  and a former president determined to whip up anger, and the recipe for terrorism seems clear.

And, indeed, as we saw on Jan. 6, that combination can spill over into political violence that shakes the foundations of the Republic. The Jan. 6 attackers, however, don’t neatly fit the definition of terrorism, and  instead. The insurrectionists were , not exactly a nonstate actor. And they sought to achieve a specific political result — preventing Congress from formalizing the 2020 electoral victory of President Biden — rather than creating a broader psychological effect, though of course their violence did create fear and anger elsewhere in the country.

Yet lethal right-wing terrorism, traditionally defined, was lacking in 2021, with several possible explanations. The first is the aggressive campaign the Biden administration has waged against parts of this movement. The administration developed a  and made it a counterterrorism priority, in sharp contrast to Trump’s administration. The government , bringing hundreds of the Jan. 6 insurrectionists to trial. Simply paying attention to the problem makes arrests and other forms of disruption more likely and scares many of those who might organize for violence, limiting their activities.

Right-wing extremists are also . Although many rallied around President Donald Trump, in general, the believers disagree on whom to target and priorities in general. Attacks like those in Pittsburgh and El Paso enjoyed little popular support, and indeed, such violence usually backfires, making the overall cause less popular. Although attention understandably focuses on paramilitary groups such as the Proud Boys, overall, the capabilities of those in the movement are low, and they are particularly bad — as the Jan. 6 investigations indicate — at operational security, with many revealing their goals, movements and organizational structures on social media, unprompted. , if they are enforced, give prosecutors many options to stop their activities.