I had never been in a bomb shelter before winter break. By the end of my two weeks in Israel, I had visited several.

I was there with 500 other Jewish student volunteers to paint the drab, claustrophobic shelters that thousands of Israeli families called home for weeks this summer as 4,000 rockets rained down on the northern part of the country during its war with Hezbollah in southern Lebanon.

We painted flowers, we painted animals — anything to make the spaces less threatening to the children who will spend several more weeks in them when — and it is only a matter of when — Hezbollah decides it’s in its interest (or Iran’s) to start Round Two.

I hope I’m wrong. Because Round One was painful and bloody enough for the people of both countries. And as bad as they were for my friends and family in Israel, they were far worse for the people of Lebanon.

While the Lebanese civilian toll was relatively low for a 34-day conflict in one of the world’s most densely populated countries — NATO’s Kosovo campaign claimed more civilian lives per day — hundreds still died who didn’t deserve to.

Few went so far as to accuse Israel of targeting innocent Lebanese, asserting rather that the Israel Defense Forces simply didn’t exhibit enough “caution” in its pursuit of Hezbollah.

Fair enough. I think we all can agree that invading armies operating in areas with innocent people around should exercise the utmost caution. And surely however much caution one shows, it is always possible to exercise more.

Yet what these critics conveniently forgot or ignored was that in today’s wars, caution comes at a price. In war, as in life, there are tradeoffs.

In the wars of yesteryear, where uniformed armies fought other uniformed armies on battlefields far removed from civilian areas, the tradeoff was simple: Kill or be killed. Caution, in short, was rarely necessary.

In the wars of today, where uniformed armies fight bands of Islamist radicals who wear no uniforms and operate out of civilian areas, the calculus is different. Every degree of caution exercised protecting the other side’s civilians is likely to entail greater danger to one’s own civilians, not to mention the brave soldiers protecting them.

Today’s ethical soldiers and commanders face excruciating moral dilemmas, many of which they must resolve in the blink of an eye.

Do I shoot this guy who’s running toward me with what looks like a gun even though I’m not sure? Do we launch a missile at the car of this suicide bomber on his way to a blow up a bus if it entails inadvertently killing two or three civilians?

Who is a civilian, anyway? Are all people to be divided between civilians and combatants? If so, what do we consider the man who shelters combatants or keeps munitions in his basement? How about the terror group’s spiritual leaders, who bless and inspire violence but don’t necessarily order or take part in it?

I pose these questions not because I have the answers, but because there are none. Reasonable people of great moral fiber can and will disagree.

Al-Qaida et al are unbothered by these questions, a clear tactical advantage. In their eyes, the enemy is one, and all its people deserving targets — soldiers, men, women, children, babies.

While we in the world of civilized democracies can ill afford to stoop to their level, there is a limit to how much of our own blood we should be willing to spill to protect the other side’s blood. To paraphrase a line in fellow columnist Ari Rabkin’s fall column “Death and the Innocents Abroad,” I suspect that those who enjoin us to avoid civilian casualties ‘at all costs’ don’t realize how high ‘all costs’ could be.”

Even the Israel Defense Forces, who have waged counter-terrorism operations with more caution than any army in history — I challenge anyone to provide me with a counter-example — still operates by a principle that should animate the armies of every sovereign nation: The lives of one’s own citizens take precedence over the lives of other nations’ citizens.

A grisly tradeoff, I admit. Stark in its win-lose calculus. It’s why this country and others should avoid war whenever possible and strive for win-win diplomacy. And yet most of us know in our hearts that there have always been and will always be situations in which war really is the only option to preserve peace and justice. That means, unfortunately, that innocent people will continue to die — that is, until either we have refined the perfect weapons or our enemies have stopped using civilians as shields,

And in the age of nuclear, biological and chemical weapons, the stakes are higher then ever. Even the most principled leaders may be forced to make decisions that allow innumerable thousands of innocent people to die in one fell swoop in order to prevent an equal number of their own citizens from suffering the same fate.

It’s a decision that has been made at least once in our country’s history …

At the end of World War II, President Truman ordered atomic weapons to be dropped on the cities of Hiroshima and Nagasaki to facilitate a Japanese surrender. About 200,000 people were killed, but the bombs had their intended effect. Japan wove the white flag, and the planned invasion of the mainland was averted, saving as many American (and Japanese) lives as the bomb had ended.

And it’s a decision that could be forced upon another country (guess who) sooner than you think …

Over the past few months, even in the face of economic sanctions and international isolation, Iranian President Mahmoud Ahmadinejad has edged his country closer to nuclear weapons as he continues threatening that the Jewish State will be “wiped off the map.”

Recent reports suggest that Israel is preparing an air campaign to destroy Iran’s reactors before the country reaches the technologically crucial “point of no return”.

This shouldn’t surprise anyone. In 1982, Israel launched a successful air attack on Iraq’s Osirak nuclear reactor. And yet, a strike on Iran would be infinitely more difficult. The Iranians, having learned from Iraq’s mistakes, have dispersed their nuclear facilities throughout the country. It raises many strategic questions

And moral ones. Many of Iran’s facilities are near civilian areas. A strike would result in the deaths of thousands, maybe tens of thousands.

And yet the alternative could be much worse. A nuclear-armed missile that hits the heart of Tel Aviv would kill two million people. A retaliatory strike on Iran would kill millions more.

Those who would tell Israel not to execute such a strike are essentially asking it to play Russian Roulette with its existence.

It may do just that, deciding that the political, military, and moral costs of a strike outweigh the risk of staying put and hoping for the best. And yet only Israel has the right to make that decision

The choice will be strategically excruciating. It will be morally troubling. And it will be made by the time you finish finals.

Ben Birnbaum is a junior in the College of Arts and Sciences. He can be reached at bhb9@cornell.edu. Infomaniacs Anonymous appears Tuesdays