Cluster munitions ban

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Cluster munitions / submunitions / bomblets / cargo rounds - there are many words warheads that contain many smaller warheads to increase effectiveness.

The principles that make such munitions are simple:
Fragments lose velocity quickly, so it's much more efficient to use many small diameter fragmenting charges than a single large one.
Many small shaped charges have a higher chance of a direct hit than a single warhead.
Many small incendiary charges have a better chance to start serious secondary fires quickly than a single large one.
Several smart submunitions can cover a larger area and potentially hit more targets at once than a single smart submunition.
Finally, the opportunity to scatter many mines at once covers a large area, and more easily than many smaller delivery munitions with only one mine each.

The introduction of DPICM on a large scale decades ago increased the effectiveness and changed the artillery's effects (many small, almost impossible to treat fragment wounds instead of few small ones, for example).
The armies of wealthy nations have usually more DPICM munitions than classic 'unitary' high explosive shells (albeit the effectiveness against tanks was overestimated by the West).

There's not only the spiral of military technology, but also politics, though. It's not really unreasonable to expect a politically effective ban on submunitions which was drafted this year and will begin the ratification process next month. The reason is the sometimes terrible dud rate (on the order of 10% although many models have less than 1% duds) that had long-lasting land mine-like effects (not necessary with proper technology like capacitator-depending fuzes or a biodegradable shell matrix, but the political damage was done).

This might become an extremely important step backwards.

First, it's necessary to evaluate the effectiveness of air attack, artillery and heavy mortars without cluster munitions.
* Air attack might not be affected very much as the trend went towards guided unitary warheads anyway.
* Heavy mortars (120mm) might not be affected very much because unitary (HE mortar shells are still quite common anyway.
* Artillery (especially multiple rocket launcher systems like MLRS) would lose a lot of its effectiveness per artillery piece if cluster munitions were withdrawn.

Better, non-cluster munitions for the artillery (smart shells like SmArt would be retained) including better control of fragmentation patterns might help to compensate for this, but that's rather an approach for the military-industrial complex as it's about hardware procurement.

Armies that remove cargo round stocks need to re-evaluate their requirements for artillery quantity - a reduction of artillery quality by x % might require a compensating increase of artillery quantity by y %.

Furthermore, smaller artillery calibres than 155mm might become more advantageous than before. This applies especially to guns that need to be lightweight anyway; mountain/airborne guns which were usually 105mm guns since the 50's but with a trend to 155mm at least in the 90's.
Denel's 105mm long-range howitzer G7 a.k.a. Leo 105 might have been a more timely design than previously thought as well.
That gun doesn't offer major advantages offer the competitor 155mm M777 other than the virtues of smaller shells (fragmentation efficiency, less ammunition bulk & weight) until it'll be redesigned for lower weight (underway).

Multiple rocket launchers may require an even more thorough assessment. Their classic strength was the near-instantaneous coverage of a target area - this was greatly enhanced by the use of DPICM, which became the almost only munition for MLRS.
Rockets can especially easily be adapted for guided operation - thanks to fins for steering and rather gentle acceleration. Maybe guided munitions for MLRS (at least the large types with a larger than 110mm calibre) will get more attention and funds in the future than without a cluster munitions ban.

Finally, we can expect more attention to proximity fusing (which increases the efficiency of fragmentation shells). This works usually with radio frequency technology - essentially tiny radars not larger than normal fuses and pre-set to detonate at a certain altitude over ground. The principle possibility to jam and therefore de-value such fuses was demonstrated already in WW2. ECCM (electronic counter-countermeasures) to protect against jamming was introduced long ago, but can this be trusted?
Jammers were reduced to backpack size as early as in the 90's (Shortstop). Such jamming technology wasn't in large-scale use by adversaries of Western armies so far, which explains the low degree of attention.
There's an apparently jamming-proof proximity fuse technology more similar to laser ranging than radar. It measures the distance only forward, not all-round and is therefore not suitable for other proximity fuse applications like anti-air missiles.
Finland's company Noptel has such a fuse for mortar bombs, for example.

The ban on cluster munitions might bend many military technology and organization trends related to artillery.

S O

edit 2008-12-07:
This graphic illustrates the loss of efficiency (albeit neither unitary HE shell fragment distribution nor cargo round submunition dispersion are perfectly circular).
source
The diameters are 100 m and 350 m.
The source has also rather distasteful photos about the more difficult to treat wounding patterns of submunitions.