In the latest bout of blood and ruin in the Middle East, a question still reverberates from Jerusalem to Beirut and beyond: Why? Why did Hezbollah's guerrillas provoke an Israel already under pressure elsewhere? Why did Israel hit back a thousand-fold, risking condemnation and untold consequences?

Veteran observers see miscalculation, hidden motives, a military blunder.

Hezbollah itself says it didn't expect the furious backlash of Israeli bombs and artillery barrages that have battered Lebanon since July 12, when the Islamic group's militiamen killed three Israeli soldiers and seized two others in a cross-border raid.

"Hezbollah miscalculated,'' said political scientist Farid Khazen, a Christian member of Lebanon's parliament. They expected pinprick return fire, and then backroom dealing to swap three Lebanese prisoners for the Israelis, he said.

"But they misread the changing international and regional situation -- September 11, the Iraq war, the fact Israel had a kidnapped soldier in Gaza. Now with two in Hezbollah's hands, that's a recipe for Israel to go completely wild.''

Events in Lebanon, meanwhile, had supplied the ingredients for Hezbollah's bold action.

In "national dialogue" sessions that began last March, talks among Beirut's sectarian and political factions had focused on Hezbollah, building pressure on this last armed Lebanese militia to disarm, as called for in a UN resolution.

The Shiite cadres needed to revive their cause, said Edward Walker Jr., a veteran U.S. Mideast diplomat.

"Hezbollah had been losing ground in southern Lebanon because its real claim to fame was in standing up to Israel'' until 2000, when Israeli occupation troops withdrew from Lebanon's south, said Walker, president of the Middle East Institute in Washington.

"Now there was no Israel to stand up to anymore."

But there were still the prisoners. Analysts believe Hezbollah wanted to link a Lebanese-Israeli exchange with a swap of Palestinian detainees for the soldier seized June 25 on the southern Israeli border by Gaza's Hamas fighters.

"Hezbollah acted out of solidarity with Hamas, to pre-empt Hamas, to get a grip on prisoner exchanges and establish itself in a prominent role," said Israeli analyst Yossi Alpher, an ex-intelligence official.

Some speculate Hezbollah's July 12 raid into northernmost Israel may even have been timed to scuttle an imminent Palestinians-only deal mediated by Egypt.

The sudden "second shoe'' on the northern border proved too much for the Israelis, said Daniel Kurtzer, U.S. ambassador to Israel in 2001-2005.

"If not for the Gaza situation, they might have responded in a more traditional tit-for-tat way - bloody noses and then ending up trading prisoners," Kurtzer said.

Instead, Israel responded with devastating air and artillery attacks on Lebanon, extending beyond Hezbollah military targets in what analysts see as an effort to pressure other Lebanese parties into neutralizing Hezbollah.

"I think the Israelis reacted as they did because they felt for the first time in Gaza, and again in south Lebanon, they are vulnerable, their invincibility was for the first time compromised,'' said Jordanian commentator Hasan Abu Nimah.

They're vulnerable, in particular, to the missiles Hezbollah has fired back, longer-range than ever before.

The Israeli retaliation was "disproportionate to the incident, but proportionate to the threat," said Alpher.

Could things have been different? Perhaps, said Kurtzer - if Israel's military hadn't blundered.

The Gaza kidnapping has already been officially blamed on an Israeli "operational failure.'' In the north, Hezbollah long boasted it would grab Israeli soldiers. It tried and failed last November.

"I left as ambassador last September, and for at least six months before that Hezbollah was trying to do what it did recently,'' Kurtzer said. "The Israelis have to analyze how they failed so miserably, allowing it to happen knowing they were trying to do it."