Israel just proved that its new Iron Dome system can repel Hamas' short-range rockets and missiles. The bad news: Those weapons are nothing compared to the more advanced missiles that Hezbollah and Iran can throw at Israel, which would surely overwhelm Iron Dome. That's why Israel, and America, are already looking into the missile defense systems that come after Iron Dome – including ones that rely on lasers.

The Israelis can justly say their system worked better than American and Israeli skeptics (and Hamas) anticipated. Five Iron Dome batteries destroyed some 421 Qassam rockets and Iranian-made Fajr-5 missiles launched from Gaza, for an interception rate of between 80 and 90 percent. (Hamas fired over 1,500 projectiles, but Iron Dome ignores those that don't impact populated areas.) It kept Israeli casualties far below Palestinian ones and might have convinced Prime Minister Benjamin Netanyahu he didn't need to re-invade Gaza. All this for a cost of under $30 million per interception.

All this has Israel pumping its fist. Uzi Rubin, a former Israeli missile defense official, boasted that Iron Dome outperformed the U.S.' Patriot missile and showcased "Jewish genius with blue and white [i.e., Israeli] technology." (Iron Dome was jointly developed with the U.S., but whatever.) And already Rafael, the company behind Iron Dome, is pledging to up its success rate to 95 percent in the next several months as it and the Israel Defense Forces sift through the launch data.

The thing is, Hamas is peanuts. Its Qassams and Fajr-5s are unguided systems, unsophisticated compared to the missile arsenals of Hezbollah and Iran, which include ballistic missiles. Even a souped-up Iron Dome would probably be overwhelmed by those. So as encouraged as Israel is by Iron Dome's success, it's already scaling upward, to more powerful interceptor-based missile defenses intended to blunt a layered assault from Hamas to Hezbollah to Iran. Some, however, doubt that a bullet is the right instrument for stopping another bullet, and would prefer to use the laser weapons the U.S. is developing.

Just days after Wednesday's ceasefire with Hamas, it prominently tested Iron Dome's big brother, called David's Sling (and sometimes "Magic Wand"). Whereas Iron Dome's stated maximum range is 45 miles (and is probably shorter in reality), David's Sling's interceptors are designed to hit incoming missiles from up to 200 miles away. If it works as intended, David's Sling should protect Israel against the longer-range missiles that Hezbollah possesses M600, Zelzal, other Fajr models; and perhaps even the Scud ballistic missiles Israel contends Hezbollah got from Iran or Syria.

David's Sling and Iron Dome have another brother, the Arrow. The Arrow has been in development for years and was originally conceived of as a Scud-stopper. Like some American anti-ballistic missile systems, the Arrow family of defenses is designed to stop a ballistic missile upon re-entry into the Earth's atmosphere – principally, Iran's Shehab-3. Over the summer, Israel upgraded the hardware, software, sensor array, interceptors and "Green Pine" radar on the Arrow-2; and an Arrow-3 is on the horizon that can reach twice its predecessor's altitude. That's likely intended to blunt the impact of Iran's forthcoming the Iranian Sejjil-2 medium-range ballistic missile.

You can think of Iron Dome as the bantamweight, David's Sling/Magic Wand as the middleweight and the Arrow as the heavyweight. And viewed together, you can see what Israel fears: a concerted barrage from Iran and its proxies that comprises everything from unguided Qassam rockets to Sejjil-3 ballistic missiles. That scenario brought U.S. Patriot missile batteries, Aegis ships and some 3,500 troops to Israel last month for the largest joint missile-defense exercises ever between the two allies, and you might hear more on the subject on Thursday, when outgoing Defense Minister Ehud Barak visits the Pentagon.

But some think hitting a bullet with another bullet is the wrong paradigm for missile defense. One Ha'aretz writer, Reuben Pedatzur, pines for Northrop Grumman's Skyguard chemical laser, which would burn through projectiles after picking them up on radar. In the pre-Iron Dome days, residents of southern Israel once sued the Israeli government to bring Skyguard to their communities. And it's worth noting that on Tuesday, rival Lockheed Martin claimed its own developmental laser system, the Area Defense Anti-Munitions, shot down four "small caliber" rockets from about a mile away in recent testing.

Except that laser-based missile defenses have been promised for decades and are never quite there yet. Rubin, the former Israeli missile defense official, blasted Skyguard in Ha'aretz on Tuesday as "simply unrealistic," noting that the U.S. doesn't even use it in Afghanistan, where its bases are frequently rocketed. And the U.S. Navy, which has sunk a lot of money into developing laser defenses for ships, still doesn't consider its most mature solid-state lasers ready to burn through missiles this decade.

Still, David's Sling and the upgraded Arrow have years to go before they're ready, and their own trials by fire might not go as well as Iron Dome's. Meanwhile, Hezbollah is pledging to launch "thousands of rockets" if Israel attacks, and the threat of a war with Iran hasn't abated. If Hezbollah, or Iran, follow through on that threat, Iron Dome's limits might become as visible as its successes just were.