With the United States involved in a shooting war in Libya, the launch of several mortar shells from Gaza into southern Israel last weekend didn’t generate much attention. But close observers of the Middle East understand that this unexceptional event — after all, terrorists in the Islamist-run strip have sent thousands of rockets and other missiles into Israel seeking to kill civilians in the last decade — betrays the tensions that are simmering among the Palestinians.

Fortunately the mortar fire hurt no one but what was interesting was Hamas’s willingness to take responsibility for the incident rather than, as its usual practice, fobbing it off on minor terrorist groups. So why, we must ask, would Hamas, which has kept the level of terror attacks from Gaza low enough to maintain the uneasy cease-fire it has had with Israel since Operation Cast Lead ended in January 2009, seek to raise the temperature in the region?

The answer is to be found in the basic equation of Palestinian politics. In the bizzaro world of Palestinian nationalism, political movements earn their bona fides not by acts of statesmanship or state building but by shedding blood or at least making a show of bloodletting. While the democratic ferment sweeping the Arab world has seemingly had little impact on the Palestinians, it would be wrong to think that they are indifferent to the struggles being waged elsewhere against autocrats and dictators. But so long as either Hamas or its Fatah rivals that run the Palestinian Authority in the West Bank can keep people focused on hatred for Israel, we may assume that Palestinian democracy will remain a theoretical subject. PA leader Mahmoud Abbas has been trying to manipulate this spirt into a call for Palestinian unity in which Fatah and Hamas will somehow come together. Whether Abbas seriously believes such a thing is possible, and he appears to be smart enough to know it is not, such rumblings represent a threat to Hamas. They will always treat such challenges to their absolute and tyrannical rule in Gaza as a deadly threat. Thus, the firing from Gaza and the counterattack it generated from Israel were probably linked to Abbas’s unity pleas and the demonstrations in support of the idea, which were quickly suppressed by Hamas.

But the question is whether this nasty exchange is the end of this episode. In a speech to the Knesset today, Israeli Prime Minister Benjamin Netanyahu sent a strong message to Abbas. By declaring that the PA leader must choose between peace with Israel or with Hamas, Netanyahu was doing more than merely reminding him that Israel will never tolerate Islamist control of the West Bank in addition to Gaza. Israelis understand that whenever Palestinians vie for popularity, Jews have a tendency to get killed. The talk of an Abbas visit to Gaza for more talks with Hamas about a unity plan is ominous not so much because there is a real danger that the a coalition between Fatah and its Islamist foes will become a reality (though that possibility cannot be entirely discounted) but because such rumblings may inspire the two movements to prove their worthiness to their constituencies by shedding some Jewish blood. With Hamas engaged in a major arms buildup (the seizure by the Israel Defense Forces of a ship last week laden with Iranian arms intended for Gaza may have been just the tip of the iceberg of this development), the potential for violence and heightened instability is real.

Though the Obama administration is understandably distracted by its involvement in Libya, Washington must second Netanyahu’s warning. Abbas depends on both the United States and Israel for his survival and he must understand that if he foolishly stirs the fires of Palestinian nationalism in order to distract West Bankers from their own lack of democracy, Israelis are not the only ones who will be burnt.