By Greg Miller and Scott Wilson
The Washington Post
The Sept. 11, 2001, attacks led to a massive buildup of security to make the country safe. Subsequent plots, including attempts to conceal bombs in shoes and underwear, prompted hasty additions to that edifice, as officials sought to fill in cracks that terrorists might exploit.
The bombings at the Boston Marathon, carried out by two young men who immigrated to this country about a decade ago, are likely to yield a more frustrating security postmortem.
So far, there have been no calls for a major addition to the nation's counterterrorism infrastructure, in part because it is difficult to identify a realistic measure that might have prevented the attacks.
Instead, U.S. officials and counterterrorism experts said that, while the bombings may lead to incremental changes in efforts to secure such events, they exposed the limits of the extraordinary defenses erected over the past 12 years.
The United States has spent billions of dollars on counterterrorism efforts during that span, an investment that has accomplished much of its aim. Overseas operations have pushed al-Qaida to the brink of collapse, and domestic steps have dramatically reduced the country's exposure to an attack of the scale and sophistication of Sept. 11.
But the Boston bombings highlighted a lingering vulnerability that officials consider impractical, if not impossible, to eliminate. It centers on small-scale plots carried out by individuals who are unlikely to surface on federal radar. They rely on devices made from common ingredients like gunpowder, nails and a pressure cooker. They target public gatherings where security resources are stretched.
"There's just no way to secure many large public events, and the kind of intrusive steps we would have to take are ones that no one would be willing to endure," said Rep. Adam Schiff, D-Calif., a former federal prosecutor and member of the House Intelligence Committee. "We've always known the limits of what we could do in a free society, and this week we saw those limits in all their horror."