What all of the fuss is about...

The Israeli justification for the Gaza blockade is that they want to prevent the Palestinians from obtaining rockets or their components to launch against Israel.

Just what are these rockets, and what is their effect?

There are some excellent articles at Wikipedia on the topic, which I draw heavily from in this article, and links to the relevant articles are embedded in the text.

The term "rocket attack" is not entirely accurate. Many of the attacks were in fact mortar attacks which were reported in the media as rocket attacks. Nonetheless, there are similarities, I would prefer to call them 'missile attacks' but purists would say that such a term would also include stone throwing. Confusing, some of the Wiki articles do differentiate between rocket and mortar attacks.

The Weapons

Mortars

Details available at Wikipedia are fairly limited. There is no indication of their range, other than that they are primarily short-range weapons (I would estimate up to 5 miles, though I may be significantly wrong). I have been unable to find out what particular types of mortar are commonly used by the Palestinian militants.

A skilled operator can produce accurate fire from a mortar. The impression that I get is that mortar attacks are usually set up quickly, and not sustained for any length of time due to the likely speed of an Israeli response.

Qassam rocket

According to Wikipedia, the Qassam rocket has been in use by Palestinian militants since 2001. There are 3 variants, with the later models having increased physical size, explosive payload, and range.

They are manufactured from common materials including metal tubing and chemical fertiliser, and either home made or military or industrial grade explosive payloads.

They do not incorporate any guidance systems and are therefore highly inaccurate. They typically have a range of 3-10 km (2-6 miles)

al-Quds

Details of this type of home-made weapon are sparse at Wikipedia. It appears have verys similar characteristics to the Qassam rocket and has been in use since 2006. A video of a larger version, the Quds-4 has apparently been released by the Islamic Jihad group.

Military-grade rockets

Wikipedia reports that 122 mm military rockets similar to those used at ammunition by Russian Katyusha and Grad multi-barrelled rocket launcher systems (MBRL). Although these rockets have a much larger range (30-40 Kms, 18-24 miles) and generally more effective explosive payload, without the appropriate launching systems they are highly inaccurate.

The scale of the threat

Let's examine the scale of the threat. Information at Wikipedia is broken down as follows:

2001- January 2009

More than 8,600 rockets were launched at Israel from Gaza, resulting in 28 fatalities and "several hundred" injuries.

2009

566 rockets were fired during the year, most of these (406) during the Israeli invasion of Gaza which finished on 18th January that year. These figures do not include mortar attacks. I can find reports of 3 fatalities and 186 injuries as a result of these.

2010 (up to and including 3rd June)

A total of 88 missile attacks (40 mortar, 48 rocket) caused 1 fatality and 6 injuries. An additional 2 attempted rocket launches were prevented by Israeli action.

Totals, 2001 - June3 2010

Rocket attacks: 10,014
Fatalities: 32
Injuries: in the order of 1,000 or less

Analysis

As a military weapon, Palestinian militant rockets are ineffective. They have a kill-rate of 0.003% and an injury rate of in the order of 10%, i.e. 9 out of 10 rockets don't hurt anyone. There are two main reasons for the lack of effectiveness; the low-level of technology employed, limiting the accuracy and range of the weapons, and the Israeli 'colour red' missile warning system which provides communities with some notice of imminent attacks.

In some cases, rockets and mortar shells don't even reach Israeli territory.

There is however a psychological effect on Israeli (and Palestinian) communities in range of the missiles which should not be discounted.

By comparison to the 32 fatalities over a period of 9 years suffered by Israel due to missile attacks averages 3.55/year. Over a 28-year period, the IRA killed 1,800 people, an average of 64.28/year.

A note on the effectiveness of the Gaza blockade

As stated in the introduction, the Israelis use the rocket attacks as a justification for the blockade on Gaza. The blockade started in 2007. In that year, there were 1,639 rocket attacks. In the first 6 months of the following year, there were 2,378, after which the rate dropped drastically following the announcement of a cease-fire by Hamas. The implication is that the blockade has no effect on the incidence of rocket attacks against Israel.