BBC Correspondent Jim Muir, who has been reporting on the current conflict from the southern Lebanese port city of Tyre, has covered the upheavals in Lebanon since the original crisis erupted there in 1975.
In the second of a two-part series on how this conflict compares with previous ones, he examines Washington's changing role.
Previous eruptions of violence that began in a roughly similar manner, such as the 1996 Grapes of Wrath bombardment, were curtailed at a much lower level than the current paroxysm.
Israel says any settlement must be based on the defeat of Hezbollah
One major difference this time is that Israel enjoys an indulgence from Washington far beyond anything previous, essentially giving it a free hand.
While previous administrations, despite commitment to the strategic alliance with Israel, kept at least some distance in earlier crises, the US under George W Bush immediately adopted Israel's primary war aim.
There could be no ceasefire until the "root problem - Hezbollah is addressed". Israel would not be under pressure to halt until Hezbollah had been defeated and destroyed.
The agony of Lebanon was, like the carnage in Iraq, part of the birth pains of the New Middle East for the neo-conservative ideologues in Washington.
This was Israel's contribution to the war on terror, dealing a blow to a proxy offspring of those "axis of evil" nations, Syria and Iran.
This offensive is very different from the Grapes of Wrath in 1996. A complex diplomatic process involving Lebanon, the US, France, Saudi Arabia, Iran and Syria delivered an indirect understanding between Israel and Hezbollah that successfully kept the conflict within bounds, despite the continuing Israeli occupation of the south and Hezbollah's attacks on it.
Hezbollah is willing to agree on an immediate ceasefire
This time, neither Israel nor the US wants to accept Hezbollah as a party to anything, nor do they want its patrons Syria or Iran to be involved, except apparently in a capitulation.
For them, any settlement must be based on the defeat of Hezbollah and the humiliation of its Syrian and Iranian sponsors.
If an increasingly isolated US, with anaemic support from Britain, continues to support or even encourage Israel's absolutist approach, the consequences could be dire both in Lebanon and in the wider region.
Israel would continue with a prolonged campaign of destruction and running warfare in southern Lebanon, with more destructive raids further north.
There are signs of a rapprochement between radical Sunni and Shia factions which could rebound massively on the US
That situation would be unlikely to remain static and confined.
Already, there are signs of a rapprochement between radical Sunni and Shia factions which could rebound massively on the US if it gains wider ground.
The Hezbollah operation of 12 July was apparently launched at least partly in support of the embattled (Sunni) Hamas in Gaza, perhaps at the prompting of their mutual supporter Iran.
So the seeds of co-operation between Sunni and Shia radical groups are already there, and - encouraged by Iran and Syria - they could start sprouting elsewhere in the region.
If Hezbollah comes under unremitting pressure in a war of attrition in Lebanon, it would be logical for Tehran to start activating more dynamically some of its many assets in neighbouring Iraq.
Bombing has destroyed Lebanese reconstruction and confidence
Iran has very close ties to most of the Shia Islamist groups which now dominate the Baghdad government, and which are watching the suffering of their fellow Shias in Lebanon with growing alarm.
Groups with armed militias, such as the Mehdi Army of radical Shia cleric Moqtada Sadr and the Iranian-grown Badr Brigade are strongly opposed to the 120,000-strong US presence in Iraq.
It is far from inconceivable that, even without co-ordination or contacts with the Sunni-based insurgency, Iranian-inspired Iraqi Shia factions could start joining in the pressure on the American forces there.
Because Israel and the Americans are insisting on victory rather than the kind of balanced compromise that prevailed in the 1996 Grapes of Wrath understanding, the confrontation risks mutating into a double existential battle merging the current regional arenas of conflict.
On one side, there is the Israeli and American project for the wider region; on the other, there are the Palestinians and Islamists and their strategic backers Iran and Syria, with the largely Sunni conservative Arab states facing increasing pressure from their Shia minorities and Sunni activists.
It is a denouement from which both the US and Israel have backed off in the past, with their respective withdrawals from Lebanon in 1983 and 2000.
War or diplomacy?
If the current course continues - and there is no sign of an imminent turnaround - there is no predicting how far and how fast the flames may spread, as Israel plunges deeper into open-ended warfare with forces challenging the very foundations of its existence.
A protracted conflict will weaken the Beirut government
There is an alternative, favoured by most of the international community apart from the US and Israel: an immediate ceasefire, followed by negotiations to address the underlying issues and stabilise the truce.
Hezbollah itself is willing to agree on an immediate ceasefire and an exchange of prisoners that would see the two captured Israeli soldiers return home.
Other issues would then be on the table, such as the disarming of Hezbollah or the merger of its forces into the Lebanese Army - a step that was already under active discussion before the current crisis blew up.
If the carnage and the overspill beyond Lebanon can be stopped, Hezbollah will find itself under strong pressure in the Lebanese political arena to agree to measures for long-term stabilisation, such as allowing the Lebanese Army to deploy down to the Israeli border.
The main Sunni, Druze and Christian political forces - Hezbollah's partners in an uneasy coalition government - were dismayed and infuriated by the sudden eruption of a war triggered without their knowledge or involvement.
The conflict has destroyed much of the country's post-war reconstruction and the growing confidence painstakingly established since the early 1990s.
The longer the war now goes on, the weaker and less relevant the Lebanese government will become, and the less able to exert pressure on Hezbollah and a Shia community seething with anger at the devastation visited on it.
For many of those non-Hezbollah, anti-Syrian factions in the Lebanese government, the key failure in the current crisis has been Washington's: its inability to keep the Middle East road map alive, and to address the core Palestinian issue, its total alignment with Israel, and its apparent willingness to allow Lebanon to be devastated in a proxy war of regional ambitions.
President Bush has declared that the root of the problem is Hezbollah, and that there can be no settlement until that problem is addressed.
Throughout the region, Arab moderates and radicals, Sunnis and Shias, would take issue.
For them, it goes without saying that the root of the problem is Israel's occupation of what was Palestine, and that there can be no peace until that problem is addressed, perhaps through a formula such as the land-for-peace offer endorsed by the Arab nations at their Beirut summit in March 2002.
Jim Muir's first article, on the historical origin of the conflict: