Hamas rulers won't be easily ousted; Israel hoping strikes will halt attacks

Israel also risks opening new fronts, including unrest that could destabilize the Abbas-ruled West Bank and possible rocket attacks by Lebanese Hezbollah guerrillas on northern Israel.

Hezbollah already proved its military prowess in its 2006 war with Israel, firing thousands of rockets. That war erupted while Israel was fighting in Gaza. Meanwhile, protests erupted across the West Bank yesterday.

Far from being cowed, Hamas leaders sounded defiant yesterday, and Hamas militants fired dozens of rockets into Israel. One Israeli was killed, and mounting Israeli casualties could turn Israeli public opinion against the offensive.

While hard-liners in Israel have demanded more aggressive action to curb Hamas rocket attacks on Israel, a difficult and bloody ground operation could backfire on Israeli political leaders who are campaigning to replace Prime Minister Ehud Olmert.

In the 2006 war against Hezbollah in Lebanon, Israel lost 114 troops in a month of fighting.

Hamas could kill an Israeli soldier, Sergeant Gilad Shalit, who was captured in 2006. Hamas also could use longer-range Grad rockets on Israeli civilians in bigger cities such as Ashkelon and Beersheva.

"Once you set the ball rolling, you cannot determine where it is going to stop," said Mouin Rabbani, a Jordan-based Mideast analyst.

Israeli leaders say they had no choice but to act.

A truce between Israel and Hamas, which took effect in June, began unraveling in early November, after an Israeli cross-border raid in Gaza. Since then, Gaza militants have fired scores of rockets. Israel held off on a major response, apparently in hopes that a new truce could be negotiated.

The government, a coalition of the centrist Kadima Party and the center-left Labor of Defense Minister Ehud Barak, could not afford to be seen as indecisive at a time when hard-line opposition leader Benjamin Netanyahu was mounting a strong political challenge. Elections are scheduled for Feb. 10.

Yesterday's strikes appeared aimed at hurting Hamas, while minimizing risk to Israeli forces.