There is nothing in Donald J. Trump’s or Hillary Clinton’s antiterrorism plans that would have had much chance of stopping the bombings in New York and New Jersey that Ahmad Khan Rahami is accused of carrying out.
The subject of how to prevent terrorism will almost certainly be a major topic on Monday night, when the two presidential candidates face off in their first debate. But the truth is that cases like Mr. Rahami’s fit neatly into no categories.
And his journey from childhood immigrant to naturalized citizen to accused terrorist shows that the debate now underway on the campaign trail is too simplistic. It fails to address the hardest and most common cause of radicalization in the United States, when personal demons morph into ideologically driven violence.
Mr. Rahami came to the United States from Afghanistan as a 7-year-old, and later became a citizen. Mr. Trump’s insistence in recent days that he has no problem with ethnic profiling might have led to tougher interrogations of Mr. Rahami when he traveled to Quetta, Pakistan, the center of Taliban power, and returned, or when he came back from there with a Pakistani wife.
The strongest indication of his leanings came in 2014 when the local police and the F.B.I. investigated Mr. Rahami’s father’s claim that his son was a terrorist. But finding no evidence, the authorities did not act. Since Mr. Rahami is an American citizen, the only way he could have been locked up without being charged was with a detention system similar to the way Japanese-Americans were placed in Japanese “internment camps” during World War II.
That was a technique, Mr. Trump told Time magazine in December, that he might or might not have supported at the time. He added that as undesirable as it would be to revive such an arrangement, in an age of terrorism, “war is tough.”
Mrs. Clinton’s approach would be to rely on countermessaging to prevent radicalization and to try to recognize early signs of extremism. But no one seems quite certain how Mr. Rahami was radicalized — on the internet, during trips to Pakistan or perhaps by his new wife. And Mrs. Clinton’s approach, even its advocates acknowledge, is no guarantee — it tries to stem the tide, rather than reverse it.
Mr. Trump, in short, has described a policy of keeping potential terrorists out of the country altogether, even if that means suspending or violating America’s longstanding principles of taking in refugees and not discriminating against immigrants on the basis of their religion. Mrs. Clinton, in contrast, has argued for the vetting of immigrants — about their history or sympathy for radical ideology — but working to counter extremists messages or behavior.