According to Bismarck’s best-known maxim on Europe’s most troublesome region, the Balkans are not worth the bones of a single Pomeranian grenadier. Americans could be forgiven for harboring similar sentiments after the murder of two U.S. airmen in Germany by a Kosovar Muslim.

Remember Kosovo? Me neither. But it was big at the time, launched by Bill Clinton in the wake of his Monica difficulties: Make war, not love, as the boomers advise. So Clinton did — and without any pesky U.N. resolutions, or even the pretense of seeking them.

Instead, he and Tony Blair and even Jacques Chirac just cried “Bombs away!” and got on with it. And the left didn’t mind at all — because, for a modern western nation, war is only legitimate if you have no conceivable national interest in whatever war you’re waging.

Unlike Iraq and all its supposed “blood for oil,” in Kosovo no one remembers why we went in, what the hell the point of it was, or which side were the good guys. (Answer: Neither.) The principal rationale advanced by Clinton and Blair was that there was no rationale. This was what they called “liberal interventionism”, which boils down to: The fact that we have no reason to get into it justifies our getting into it.

A decade on, Kosovo is a sorta sovereign state, and in Frankfurt a young airport employee is so grateful for what America did for his people that he guns down U.S. servicemen while yelling “Allahu akbar!”

The strange shrunken spectator who serves as President of the United States, offering what he called “a few words about the tragic event that took place,” announced that he was “saddened,” and expressed his “gratitude for the service of those who were lost” and would “spare no effort” to “work with the German authorities” but it was a “stark reminder” of the “extraordinary sacrifices that our men and women in uniform are making . . .”

The passivity of these remarks is very telling. Men and women “in uniform” (which it’s not clear these airmen were even wearing) understand they may be called upon to make “extraordinary sacrifices” in battle. They do not expect to be “lost” on the shuttle bus at the hands of a civilian employee at a passenger air terminal in an allied nation.

But then I don’t suppose their comrades expected to be “lost” at the hands of an army major at Fort Hood, to cite the last “tragic event” that “took place” — which seems to be the president’s preferred euphemism for a guy opening fire while screaming “Allahu akbar!”

But relax, this fellow in Frankfurt was most likely a “lone wolf” (as Sen. Chuck Schumer described the Times Square Bomber) or an “isolated extremist” (as the president described the Christmas Day Pantybomber).

There are so many of these “lone wolves” and “isolated extremists” you may occasionally wonder whether they’ve all gotten together and joined Local 473 of the Amalgamated Union of Lone Wolves and Isolated Extremists, but don’t worry about it: As any Homeland Security official can tell you, “Allahu akbar” is Arabic for “Nothing to see here.”

Bismarck’s second best-known maxim on the region is that the Balkans start in the slums of Vienna. The Habsburg imperial capital was a protean “multicultural society” wherein festered the ancient grievances of many diverse peoples.

Today, the Muslim world starts in the suburbs of Frankfurt. Those U.S. airmen were killed by Arid Uka, whose Muslim Albanian parents emigrated from Kosovo decades ago. Young Arid was born and bred in Germany. He is a German citizen who holds a German passport. He is, according to multicultural theory, as German as Fritz and Helmut and Hans. Except he’s not. Not when it counts.

Why isn’t he a fully functioning citizen of the nation he’s spent his entire life in? Well, that’s a tricky one.

Okay, why is a Muslim who wants to kill Americans holding down a job at a European airport? That’s slightly easier to answer. Almost every problem facing the western world, from self-detonating jihadists to America’s own suicide bomb — the multi-trillion dollar debt — has at its root a remorseless demographic arithmetic.

In the U.S., the baby boomers did not have enough children to maintain their mid-20th century social programs. I see that recent polls supposedly show that huge majorities of Americans don’t want any modifications to Medicare or Social Security.

So what? It doesn’t matter what you “want.” The country’s broke, and you can vote yourself unsustainable quantities of government lollipops all you like, but all you’re doing is ensuring that when, eventually, you’re obliged to reacquaint yourself with reality, the shock will be far more devastating and convulsive.

But even with looming bankruptcy America still looks pretty sweet if you’re south of the border. Last week, the former director of the U.S. Census Bureau, Steve Murdock, told the Houston Chronicle that in Texas “it’s basically over for Anglos.” He pointed out that two out of every three children are already “non-Anglo”, and that this gap will widen even further in the years ahead. Remember the Alamo? Why bother? America won the war, but Mexico won the peace.

In the Lone Star State, Murdock envisions a future in which millions of people with minimal skills will be competing for ever fewer jobs paying less in actual dollars and cents than they would have earned in the year 2000. That doesn’t sound a recipe for social tranquility.

What’s south of Europe’s border? Why, it’s even livelier. In Libya, there are presently one million refugees from sub-Saharan Africa whose ambition is to get in a boat to Italy. There isn’t a lot to stop them.

Between now and mid-century, Islam and sub-Saharan Africa will be responsible for almost all the world’s population growth — and yet, aside from a few thousand layabout Saudi princes whoring in Mayfair, they will enjoy almost none of the world’s wealth.

Niger had 10 million people in 2000, and half-a-million of them were starving children. By 2010, they had 15 million, and more children were starving. By 2100, they’re predicted to hit 100 million. But they won’t — because it would be unreasonable to expect an extra 90 million people to stay in a country that can’t feed a population a tenth that size.

So they will look elsewhere — to countries with great infrastructure, generous welfare, and among the aging natives a kind of civilizational wasting disease so advanced that, as a point of moral virtue, they are incapable of enforcing their borders.

The nations that built the modern world decided to outsource their future. In simple economic terms, the arithmetic is stark: In America, the boomers have condemned their shrunken progeny to the certainty of poorer, meaner lives.

In sociocultural terms, the transformation will be even greater. Bismarck, so shrewd and cynical about the backward Balkans, was also the father of the modern welfare state: When he introduced the old age pension, you had to be 65 to collect and Prussian life expectancy was 45.

Now life expectancy has near doubled, you get your pension a decade earlier, and, in a vain attempt to make that deformed math add up, Bismarck’s successors moved the old East/West faultline from the Balkans to the main street of every German city.

Americans sometimes wonder why, two decades after the collapse of the Warsaw Pact, the U.S. Army still lives in Germany. The day is approaching when they will move out — if only to avoid any more “tragic events” “taking place.”