Yesterday, I noted President Obama’s comment in his Oval Office address decrying the fact that “We spent a trillion dollars at war, often financed by borrowing from overseas. This, in turn, has short-changed investments in our own people, and contributed to record deficits.” I pointed out the $1 trillion Obama cites includes not only the cost of the battle in Iraq (which he opposed), but also our military efforts in Afghanistan, Pakistan, the Arabian Peninsula, South Asia, the Horn of Africa, and other fronts across the world (which he not only supports but has even expanded).

But to put that figure in perspective, consider that from 2000 to 2009 the United States produced about $122.5 trillion of total gross domestic product (data here). So spending $1 trillion to prevent another terrorist attack comes to about four-fifths of 1 percent of the GDP the United States has produced over the past decade—less than a penny on the dollar. Seems to me that spending less than one cent on the dollar to stop another 9/11 is a pretty good investment—especially when one considers the human and economic costs of another catastrophic mass-casualty attack.