It’s okay to play defense against terrorism. That’s because we have gotten really good at defense. As the U.S. military has fought seemingly endless overseas wars, other parts of the government have simultaneously built a layered defense that has arguably been far more effective than military operations at keeping the country safe.
Consider just a few of the biggest post-9/11 reforms. The U.S. government established the Department of Homeland Security, federalized aviation security, and nearly quintupled homeland-security spending. For all the jokes that travelers make about the TSA, the agency has quietly developed procedures and technologies to detect explosives anywhere a terrorist could hide them—in luggage, liquids, electronic devices, shoes, even underwear—and made it far harder for terrorists to board an airplane with a false identity.
The FBI has completely reinvented itself as a national-security agency and dedicated thousands of agents and analysts to the mission. It has worked closely with state and local law enforcement, which have made their own investments in counterterrorism. As a result of such efforts, the federal government has successfully prosecuted nearly 700 international terrorism cases. Countless more terrorist suspects have been deported or extradited to other countries for prosecution. The FBI assesses that America’s greatest terrorist threat today comes from lone actors—both those inspired by al-Qaeda and ISIS as well as those motivated by white nationalism or other racial or ethnic animus. The agency has thousands of open investigations into a threat that by definition cannot be disrupted with overseas military operations.