When lone wolf slips through the net

First the San Bernardino shooting, then the Pulse nightclub massacre, and now the Chelsea bombings: A recent spate of attacks by homegrown terrorists threatens to erode the country’s trust in the nation’s anti-terrorism efforts and push national-security

The Chelsea episode in particular appears to have been another near-miss on the part of the FBI, which looked into the alleged bomber, Ahmad Khan Rahami, in 2014. Rahami returned from spending several months in and around the terrorist haven of Quetta, Pakistan, that year. Then, following an episode of domestic violence, the FBI got word that Rahami may have radical leanings. Rahami’s father claims he raised red flags in interviews with federal law enforcement officers. But government officials have challenged his account in conversations with reporters, maintaining that officers could not discern meaningful ties to terrorism or radicalization.

Yet Rahami was radicalizing. The results were not nearly as bloody as those of the gruesome 2013 Boston Marathon bombings. But in both cases government agents appeared to have some warning.

It is important to ask questions about what the government missed and learn from the latest case. But it is even more important for Americans to recognize that, in the real world, they cannot expect that every plot will be foiled — or even that every valid lead the government receives will result in the detection of radicalization or an active terrorist plan. The FBI has neither the resources nor the authority to aggressively pursue all of the thousands upon thousands of U.S. citizens about whom they get weak tips. And it should not — doing so would be a waste of resources and subject huge numbers of innocent Americans to unwarranted harassment based on flimsy evidence, exaggerated fears or simple prejudice. Even then, investigators would still occasionally miss things.

The record so far suggests that the FBI is doing a decent job thwarting would-be terrorists. The Wall Street Journal reports that the agency has stopped the plots of more than 90 homegrown terrorists over the past two years. Compared with the number of successful homegrown attacks, that represents a fairly good success rate — particularly when gauged against the increasing scope of the danger. The FBI is engaged in 900 terrorism investigations across the country, according to CNN. But that no doubt represents only the tip of the iceberg, as many cases are examined without opening a formal investigation. The number of tips, meanwhile, is much larger still.

The threat is growing harder to deal with: A recent report from New America finds that the number of terrorism cases has surged since the rise of the Islamic State, which, unlike al-Qaida before it, uses social media to encourage uncoordinated, lone-wolf terrorist attacks.

The government’s goal must be to stop every attack. But the country must also resist overreacting when an Ahmad Khan Rahami slips through the net.