Israel’s air offensive against the Gaza Strip on Saturday should not have been a surprise for anyone who has been following the mounting hostilities in the region — least of all the Hamas movement, which invited the conflict by ending a six-month-old ceasefire and launching scores of rockets and mortar shells at Israel during the past 10 days. The initial Israeli strikes appeared to deal a punishing blow to the Islamic movement, reportedly killing several of its leaders and dozens of other militants and security force members. Inevitably, however, civilians were among the more than 200 reported Palestinian dead, and renewed Palestinian rocket fire against Israeli cities killed at least one person. While Israel could justifiably describe its action as one of self-defense, it’s far from clear that it will end up improving the country’s security — even as it risks a wider conflict.

Israeli officials say the aim of the attack is a modest one: to force Hamas to return to the uneasy and informal truce, under which Palestinian rocket and mortar fire was curtailed if not entirely stopped and Israel relaxed but did not lift its economic blockade of Gaza. Hamas’ Damascus-based leadership, which ordered an end to this “calm,” as Israel calls it, also seems to have a relatively limited objective. It demands an end to all Israeli (and Egyptian) restrictions on movement in and out of Gaza in exchange for more quasi-peace. One considerable obstacle to such an outcome is that Israel is engaged in an election campaign in which the various candidates — including the serving defense and foreign ministers — are staking out hawkish positions. The outgoing Bush administration, for its part, was quick to offer support to Israel Saturday and to blame the conflict on Hamas.

Over time, however, a fight in Gaza could be costly for Israel. Military commanders have repeatedly warned that it could lead to punishing attacks on Israeli cities, spread to the West Bank or Lebanon, or force a ground invasion that would cause thousands of casualties and leave Israeli troops stranded without an exit strategy. Israel cannot stop rocket attacks by military action alone; eventually a political deal will be needed. And any hopes its leaders have of overthrowing Hamas’ government in Gaza are probably illusory, unless a long-term reoccupation of the territory is undertaken.

While the fighting lasts — and Israeli officials were warning Saturday that it could be prolonged — Hamas’ principal sponsor, Iran, will have achieved a tactical success. Israeli diplomats have been working feverishly in recent weeks to focus international attention on the Iranian nuclear program as the Obama administration prepares to take office. They’ve been warning that the new U.S. president will have to act quickly if an Iranian bomb is to be stopped. Now, for weeks or possibly months to come, all eyes will be on Gaza — on the fighting, the continued suffering of civilians and the need for a fresh settlement. Israel might have avoided this fight, and gained a diplomatic advantage of its own, by relaxing the economic blockade. Now it will be embroiled in a costly battle that, in the end, is a distraction from the most serious threat it faces.

(This editorial originally appeared in the Washington Post.)