By Jonathan Marcus
BBC diplomatic correspondent
Tank crews have provided a significant number of casualties
One of the major military surprises of the fighting in Lebanon has been the apparent vulnerability of Israeli armour to Hezbollah anti-tank rockets.
No detailed figures are available and it is clear that many more tanks may have been hit than actually destroyed.
But a significant proportion of Israeli casualties have been among tank crews.
Hezbollah has also used its anti-armour weapons to bring down buildings around sheltering Israeli troops, again causing multiple casualties.
Hezbollah has fielded some of the most modern Russian-made anti-tank weapons, which the Israelis insist have come via the Syrians.
The potency of infantry anti-armour weapons is nothing new for the Israelis.
One journalist reported seeing the sophisticated Kornet
In 1973, after Egyptian forces crossed the Suez Canal, Israel tank units learned the hard way about what Russian-made missiles could do.
The Egyptians put across the canal large numbers of soldiers armed with wire-guided Sagger missiles.
As long as the operator kept the target tank in his sights, signals sent along the unreeling wire would guide the missile to its target.
As counter-attacking Israeli tanks raced towards the canal, they were met by barrages of these missiles.
You can be sure Israeli Defence Forces planners... will be studying these engagements in detail
Commanders spoke of vehicles emerging from the fighting festooned with wires from the missiles, and many tanks were destroyed.
Since then a complex design battle has been underway between the tank and the infantry anti-armour weapon.
For the foot-soldier the key is penetration but also weight: What can easily be carried into battle?
For the tank, too, there are weight considerations as more and more armour places heavier strains on engines and running gear and also potentially limits the areas in which a tank can operate.
In Lebanon Israel has come up against some of Russia's most modern anti-tank weapons.
Crew protection was a key element in the Merkava tank's design
The AT-13 Metis or Saxhorn is a modern tube-launched successor to the Sagger.
Its tandem-shaped warhead can punch through armour of up to 46cm (18 inches) thick.
The tandem warhead is designed to counter reactive armour as used on many Israeli vehicles.
Reactive armour is essentially made up of explosive pads or bricks on the outside of the tank which explode outwards when hit by an incoming missile.
This disrupts the effect of the missile warhead, which needs to impact upon the surface of the tank to achieve its penetrative effect.
A twin or tandem charge is designed to get around this.
The first warhead triggers the reactive armour and the second penetrates the tank.
Hezbollah is also reported to have used the RPG-29; a shoulder-fired weapon, again with a tandem charge.
And a journalist from the London-based Daily Telegraph newspaper reports also seeing abandoned Kornet missiles in Lebanon.
The Kornet was first shown by the Russians in 1994 and represents state-of-the-art technology.
It has either an optical or a thermal sight - effectively "riding" a laser beam to its target. It again has a tandem warhead.
It has a range of up to 5km (three miles) and is said to be able to penetrate armour up to 1,200mm thick.
Hezbollah has fielded some of the most modern weaponry
The Kornet has been exported by the Russians to only a few countries, including Syria.
And all the evidence suggests that the Syrians have passed them on to Hezbollah.
Israel is so concerned that it has despatched a team of officials to Moscow to show the Russians the evidence of what they say can only be Syrian weapons transfers.
In the longer term, the experiences of 1973 played an important part in shaping the philosophy behind Israel's Merkava battle tank.
The Merkava or Chariot is among the most modern in the world, but its unique feature is the extent to which crew protection figured in its design.
Quite apart from carrying highly sophisticated armour, it is almost unique in having the engine in the front, affording additional protection to its crew.
The need for well-armoured infantry carriers that can keep pace with the tanks has led Israel to convert a large number of older tanks to carry troops.
The Achzarit is a good example. It is based on the Russian T54/T55 tank which Israel captured in large numbers during the 1973 war.
Its turret and main gun have been removed and various other changes made to allow it to accommodate a crew of three along with seven infantrymen.
But all of these enhancements have not proved sufficiently effective against the most modern anti-tank systems operated by determined fighters on the ground.
You can be sure Israeli Defence Forces planners and indeed military observers from around the world will be studying these engagements in detail.
Part of the answer may be to adopt new kinds of armour.
But, as ever, part of the answer will be tactical - changes to the way tanks are employed and the way they operate in concert with other elements of ground-power, like infantry and artillery.