Depleted by a blockade and sidelined by a Palestinian unity deal, Hamas is more isolated than ever after Israel crushed its West Bank networks in response to the killing of three teens, experts say.
"Hamas is responsible and Hamas will pay" for the killings of the Israelis who disappeared in the southern West Bank on June 12, Prime Minister Benjamin Netanyahu said late Monday before his air force pummelled the Gaza Strip.
The Israeli leader's warning came just hours after the bodies of the three students were found.
Hamas relinquished administration of Gaza under a unity deal with the Palestine Liberation Organisation that sought to end years of rival governments in the coastal strip and the West Bank.
But any hope the agreement might give the blacklisted Hamas breathing space was quickly dashed as Israel blamed the Islamist movement for the teenagers' kidnap.
Israel responded to the abductions by detaining 276 Hamas members in a sweeping arrest operation in the West Bank.
As Israel's cabinet mulls its response -- with some ministers intent on invading Gaza and others keener on targeted strikes -- Hamas has said it will "unleash hell" in the face of an Israeli "escalation" of violence.
The Islamist movement, already weakened by a blockade of Gaza since 2006, could nevertheless face considerable wrath, experts say.
- 'War a possibility' -
"Deterioration into war is a possibility. It depends on what kind of blow Israel chooses to deal," West Bank-based political analyst Mohammed Muslih told AFP.
Israel may also feel pressure to deal a strong blow to Hamas to quieten Israel's hardliners and assuage public anger at the failure to find the teens, Muslih added.
A senior Hamas member agreed.
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"Finding the bodies was a shock to Israel and showed it up as failing, exposing an intelligence deficiency. So Israel wants revenge and for Hamas to pay the price, whether it's responsible or not," said Ghazi Hammad.
Hamas has insisted it had no information about the kidnap, and has neither confirmed nor denied responsibility for the killings, despite Israel fingering two of its members for the abduction.
The tactic of keeping its distance from the abduction could "soften the blow" for Hamas, according to Walid al-Mudallal, politics professor at Gaza's Islamic University.
"But Hamas will not remain silent if it's targeted. Hamas will rock the table if it comes to a choice of going down with a fight or going down quietly," he said.
Israeli political commentator Alex Fishman, writing in Yediot Aharonot newspaper, squarely placed responsibility for the kidnappings on Hamas' shoulders, suggesting if not a direct order, the incident was part of a general strategy.
- 'Shot itself in foot' -
To that end, the Islamist movement dealt itself a blow, he wrote.
"Hamas pinned its hope on the Palestinian reconciliation government, on its growing closeness with the West and on the Arab world -- mainly Egypt. But then the kidnapping came along and reshuffled the deck for Hamas.
"It simply shot itself in the foot."
The reconciliation deal, signed late April, saw a unity government of independents sworn in on June 2, backed by Hamas and rivals Fatah, and the Islamist movement relinquished control of Gaza, where it had its own government since 2007.
Commentators expected the group to return to the background, away from the responsibilities of government, and recuperate while hiding behind the internationally recognised Palestinian Authority, headed by president Mahmud Abbas.
Israel's arrest of hundreds of Hamas members after the kidnap, in an operation where the army also killed five Palestinians, quickly snuffed out hope of a grassroots recovery.
And as Israel's government mulls its response to the killing, some observers fear the worst for Hamas.
Israel will conduct a "widespread revenge" operation, according to Mudallal, who said the more than 34 overnight air strikes in the Strip were merely a "dress rehearsal for war".