Georgie Anne Geyer

WASHINGTON -- From the beginning of our formation as a big and prospering new nation, we Americans have tended to underestimate one of the great sources of our wealth and, especially, our security.

We did not like to think that anything outside ourselves was important to our success. But America had what few other countries had, and this factor protected us up to the end of the 20th century.

I speak of the simple fact that our great continent has been a land protected by the arms of the two great oceans. There may be nutters today, such as Kim Jong-un, who like to think of throwing missiles at us, but that was certainly not the case in 1776 or 1814 or even 1914.

We had to get rid of our pesky British brothers even after 1776 (they didn't take "No" for an answer) and the French (they didn't take "Non" for an answer), and we even had the Russians up in Alaska (they didn't take "Nyet" for an answer). But in the end, through hook or, yes, sometimes by crook, we stoutly pushed all of them back home.

In 1823, the Monroe Doctrine was promulgated from the White House, telling all Europeans to leave the Caribbean and Latin America alone as well. (Not that we held anything against them!)

So we settled in to our beautiful, rich continent, pretending there were no Indians here, and suffering through a couple of terrible wars that were all our own. During World War II, a few German submarines slinked up and down the Eastern Coast, but they weren't too much trouble, and we took care of Pearl Harbor with a devastating retaliation -- but entirely on our enemies' territory.

Now this has all changed; and if this bad week says anything to us, it tells us again that we are no longer a unique nation protected by those great Atlantic and Pacific oceans. They can now be breached by technology, by military inventions and by every human artifice.

This week we had the hideous travesty of decent human life at the Boston Marathon, an annual event of community if ever there was one. At this writing, we know only that two homemade bombs wreaked havoc, killing at least three and wounding nearly 200 -- but we don't know who is responsible for carrying out the attack or, especially, why.

To me -- a survivor of the early terrorism in the Middle East when the PLO was the dastardly perpetrator of the first terror attacks in the post-World War II era, mostly against air transport -- Boston looks like an American-based strike. The pressure cooker, the nails, the black bag all would seem to have American initials on them.

Then again, I may be wrong. One of the anomalies of this new age is that, as I discovered in my own coverage as a correspondent in the Middle East, everybody from the Yemenis to the Syrians to the Chinese know how to make things look American.

Still, if this attack is from some disgruntled, or crazy, or celebrity-seeking American, it would make it easier -- easier to find him, if not necessarily easier to understand.

There are two major groups of terrorism suspects in America today. The first is the American terrorist, the homegrown sadist, brooding and hoarding instruments of destruction and terror. He can be Adam Lanza in Newtown, Conn., or James Holmes in Aurora, Colo.

The second group of terrorists is, of course, the foreign terrorists belonging to some organization such as al-Qaida or that entire spectrum of groups now spread across the sands of northern Africa.

The Boston bombing doesn't look like one of theirs -- there is no claim to it, for instance, so it can't really breed fear.

We don't know enough at this point about the stunning explosion at the West, Texas, fertilizer plant on Wednesday night, just as the streets in Boston were being swept up. Coming so soon after the Boston bombings, the explosion caused one to wonder whether this was another terrorist attack -- or simply a terrifying fire.

Meanwhile, the responses of people in West and Boston, especially the amazing work of the first responders -- and all the bombings the FBI has stopped beforehand since 9/11, can make us proud, indeed.

Thursday morning, the mourning mother of a girl killed in West was quoted as saying, "It just doesn't make any sense." But it does make sense -- to terrorists. And so we need to continue what we're doing rather well -- hook into their "sense" so we can stop them forever.