The firing of rockets and mortar shells on towns in southern Israel from the Gaza Strip last week should be categorically condemned, since it targeted Israeli civilians or failed to distinguish between military and civilian targets. The perpetrators and the Hamas government which allows militant groups to fire from the territory under its control must be held accountable.

The Israeli Defense Ministry’s hasty response, however, declaring that Kerem Shalom would be closed until further notice, raised concern among those trying to transfer humanitarian supplies to Gaza. It was not clear whether the closure of the crossing was a legitimate measure in response to a real and concrete security risk to the crossing and those who work there, or if the Defense Ministry decided to react as it had in the second half of 2008: In the months leading up to the Gaza war, Israel closed the civilian crossings as punitive retribution for rocket fire, not as a response to a concrete security threat.

Residents of Gaza breathed a sigh of relief on Sunday, when Israel permitted the reopening of the Kerem Shalom Crossing and the resumption of a minimum level of supply to the Strip. The dependence on Kerem Shalom is so great because it is virtually the only goods’ crossing that remains open; every closure thus blocks the transfer of goods that are in short supply in Gaza because of the Israeli-imposed “minimum humanitarian standard”.

Since the closure of Gaza began in June 2007, Israel has systematically worked to restrict the operation of the Gaza Strip’s crossings – policies that reached a peak with the closure of the Nahal Oz crossing at the start of 2010. And so, at this time, with the exception of the grain conveyor at the Karni Crossing, the Gaza Strip is dependent on one crossing – Kerem Shalom – which was originally designed for the occasional transfer of humanitarian aid and which has limited capacity. Israel has even insisted that Egypt transfer all aid to the Gaza Strip coming from its territory via the Kerem Shalom crossing and not via its own crossing at Rafah. Last week, Egypt announced that it would permit supply from its territory only via Kerem Shalom. This dependence on Kerem Shalom is well-known to those who shoot at it and to those who allow the shooting to take place.

Israeli policies to restrict the operation of the Kerem Shalom crossing stand in violation of international agreements it has signed, which take into account situations where a security risk may occur at a particular crossing. In these agreements Israel committed to three basic principles that were intended to ensure that the Gaza Strip crossings would function on a continuous basis, even in the presence of real security threats: the operation of alternative lanes (lane redundancy) and alternative crossings (passage redundancy), as well as a commitment to the primary aim: the principle of continuous operation. Yet as of 2010, virtually all alternative crossings have been closed.

Since Israel insists on enforcing an almost total closure policy that leaves the Gaza Strip “on the edge” in every aspect of life (food, goods, electricity, cooking gas and more), every closure of the single crossing still permitted to operate, when already only minimum amounts are allowed through it, threatens to push Gaza over the edge.

According to Palestinian officials, last week Israel mounted two attempts to transport industrial diesel into the Gaza Strip via the Kerem Shalom border crossing, and not via the Nahal Oz crossing, which has until now been the only crossing designed and equipped for the transfer of fuels and gas to Gaza. Attempts to transfer industrial diesel via Kerem Shalom were also made in the previous month. In the last week, Israel transferred not one drop of industrial diesel via Nahal Oz and in the previous two weeks transferred 3.68 million liters in total- 53% of the amount required. The reports that Israel intends to close down the Nahal Oz crossing completely follow a gradual slowdown of operations at the terminal, which now operates only three days a week.

The other crossings have also been closed: Karni Crossing, which was the main trade route, has been closed since June 2007, and only one conveyer belt, used to transport produce and animal feed, has continued to operate on a partial basis since then. The Sufa crossing has not operated since September 2008 and Israel announced its permanent closure in March 2009. The transfer of goods via the Rafah crossing is prohibited. And so all of Gaza is now almost totally dependent on the Kerem Shalom crossing, which has limited capacity and was originally designed for the occasional transfer of humanitarian aid only. Now Israel apparently plans to burden Kerem Shalom with fuel and gas transports as well.

Of course, in response to rocket fire from the Gaza Strip, Israel occasionally closes Kerem Shalom too, due to what it identifies as dangers to the crossing.

The possibility that security risks would threaten the opening of Gaza’s crossings was the subject of considerable forethought. As a result, three fundamental conditions designed to ensure that the Gaza Strip crossings would operate continuously were established and agreed to by Israel:  (1) Recognition of the need to operate alternative lanes (lane redundancy); (2) recognition of the need to operate alternative crossings (passage redundancy); and (3) the primary objective which Israel committed to in the Crossings Agreement: the principle of continuous operation.

It is hard to imagine how one crossing, consisting of only one primary lane, can fulfill these fundamental conditions.

Meanwhile, Israel continues to strike against the tunnels underneath the Egypt-Gaza border, via which the majority of goods required by Gaza residents are transported, including by blowing them up.

Under these circumstances, with the sea and air routes completely blocked, the tunnels rejected as a legitimate option, and the overland crossings increasingly shut down, how exactly are the residents of Gaza supposed to get the goods they need?