Flickr/Israel Defense Forces.“Deterrence is like a popsicle. Once you take it out into the sun, it immediately begins to melt.”

So a very high-ranking Shin Bet (Israel Security Agency) official told me in Tel Aviv just over a year ago. Indeed, this has proven to be the case with Hamas. While rocket attacks from the Islamic Resistance Movement and other militant groups in Gaza decreased by around 90 percent in 2009 following Operation Cast Lead, they have been on the rise ever since.

The task Israeli Defense Forces undertook last week in Gaza is the updating of Israel’s deterrence against Hamas. And the pattern of conflict fits precisely with the premise of “tactical deterrence”—the type of deterrence states can generally hope to achieve vis-à-vis non-state militant groups.

Unlike strategic deterrence, a paradigm of total deterrence such as that which existed between the United States and Soviet Union, tactical deterrence is not perfect. Rather, it is defined by dramatically reduced rates and types of violence by the non-state group, punctuated by periods of fighting where the defending state must “update” its deterrence. The state does so by reminding the challenging non-state group that it must “settle down” or risk serious, long-term damage. In the case of Israel’s deterrence against Hamas and Hezbollah, this fits the pattern of some kind of major escalation once or twice per decade.

The updating of deterrence usually takes place when Hamas (or Hezbollah) has successfully changed “the rules of the game” between it and Israel. These rules, though not explicitly articulated, are clearly understood by both Israel and its Islamist foes and are even explicitly referred to by Israeli, Hamas, and Hezbollah leaders.

The rules circumscribe the conflict by defining what type of violence Hamas and Hezbollah can engage in and what response the militant groups should expect from Israel as a result. For example, if Hamas fires just a few rockets per month, Israel will retaliate only by bombing a few tunnels into Egypt. But if Hamas fires many more rockets, then Israel will conduct air strikes on Gaza. When Hamas reached the point that it did before Operation Pillar of Defense began, firing dozens of rockets per day, it signaled that the rules were beginning to fray and Hamas was trying to establish new rules that would allow it to act more aggressively. Israel's assassination of Hamas military commander Ahmed al-Jabari and the ensuing air campaign was an attempt by Israel to reestablish rules of the game that were favorable to Jerusalem.

Indeed, if one examines the flare-ups in the Israeli-Islamist conflict over the last 20 years, one finds that the conflict’s peaks nearly always occur when Israel feels that its deterrence is weakening and that Hamas or Hezbollah have established rules of the game that are unfavorable to Israel. In response, the IDF launches an extensive operation as a means of reestablishing deterrence—rules of the game that are favorable to Israel.

For example, in the case of the Second Lebanon War in 2006, Israeli security officials proudly admit that they broke the rules of the game that were in place with Hezbollah since Israel’s 2000 withdrawal from southern Lebanon. The 34-day war Israel launched following the killing and kidnapping of its two reserve soldiers was an attempt by Jerusalem to establish new rules whereby Hezbollah would pay a much steeper price for kidnapping soldiers and engaging in operations on Israeli territory than it had during the previous six years when the Party of God frequently attacked IDF and civilian positions inside the internationally recognized border of Israel.

The same can be said of Operation Cast Lead (the Gaza War), when Israel sought to establish a situation where Hamas could no longer fire rockets at Israeli communities in the south of the country with impunity, as the Islamists did from 2005 to 2008. In both the Gaza War and the Second Lebanon War, Israel’s strategy worked (despite harsh criticism), as attacks from Hamas and Hezbollah decreased dramatically following each conflict and tactical deterrence was established. Previous rounds of fighting between the IDF and Hezbollah in 1993 and 1996 also resulted in an updating of the rules of the game between the two sides, though with the IDF occupying Lebanon at the time, the rules were much more favorable to Hezbollah.

Much commentary and analysis from non-Middle Eastern sources has stated that the current paradigm which exists between Israel and Hamas/Gaza is not sustainable; that the pattern of the 25-year-old conflict between the Jewish State and the Islamic Resistance Movement must give way to a détente or a new regional political architecture that fundamentally changes the conflict. Such analysis is seriously flawed.

For all its pragmatism—and its leaders are pragmatic—Hamas remains an organization committed to reestablishing Muslim control over all of historic Palestine and to doing so by means of violent jihad. Israel, meanwhile, is not going anywhere, nor has any Israeli leader with a chance of being elected articulated a Gaza strategy other than maintaining deterrence against Hamas and containing the threat from it through material coercion.

As everyone who spoke directly with Israeli and Hamas leaders over the past four years knows, the latest round of fighting was an inevitability. Even if the tectonic shifts in Middle Eastern politics allowed for Egyptian (Muslim Brotherhood)-American initiative to halt the IDF’s invasion of Gaza this time, it will not change the fundamental points of the Israeli-Islamist conflict.

There are alternatives to the pattern of violence—for example, a medium-term ceasefire as I previously articulated on these pages. But strategic decisions must be reached during periods of relative calm, and there is no indication that regional and international leaders are willing to think out of the box in any case.

As such, the war between Israel and the Islamist world will likely continue to ebb and flow as it has since Hezbollah’s establishment in 1982. The Shia Islamists in Lebanon and the Sunni Islamists in Gaza may now find themselves on opposite sides of the fault line ripping apart the Arab/Muslim world. But they still stand on the same side of the battle against Israel.

The recent escalation is simply another round of fighting in the Israeli-Islamist conflict. Upon its conclusion, new rules of the game will be established. Hamas will lick its wounds and engage in a period of rebuilding and rearming. The popsicle of Israeli deterrence will once again begin to melt. And the clock will begin counting down toward the next round of fighting some months or years hence.

Rafael D. Frankel is an adjunct professor at Georgetown University where he teaches a course on the conflict between Israel, Hamas, and Hezbollah. He was previously a Middle East correspondent for The Christian Science Monitor.