Israel's campaign in Gaza is serving to expose the strategic fault lines in the Arab and Muslim world.

The essential divide is between, on the one hand, states aligned with the West - chief among them Egypt and Saudi Arabia - and on the other an alliance led by Iran, of which Hamas forms a part. Israel's action in Gaza has led to unprecedented tensions between representatives of these rival blocs. Because of the strategic importance of Egyptian control of the Rafah Crossing, this divide also has immediate practical implications for the direction and likely outcome of the current battle.

On Sunday, Hizbullah leader Hassan Nasrallah focused on the events in Gaza in a speech on al-Manar TV. Nasrallah did not limit himself to calling down fire and brimstone on Israel.

Rather, he singled out Egypt for criticism. Nasrallah echoed Hamas condemnation of Egypt for refusing to allow a general opening of the Rafah Crossing. The Hizbullah leader expressed incredulity at a statement by a senior Egyptian official holding Hamas ultimately responsible for events in Gaza. Likening Hamas in Gaza to the Shi'ite forces at the battle of Karbala (a central event in Shi'ite history), he demanded that the people of Egypt take action and force the opening of the crossing. He said that the Egyptian police would be unable to prevent this. Nasrallah noted that the opening of the crossing would enable Hamas to bring in supplies and hold out.

He reiterated these remarks on Monday, in a speech (conveyed by video link) to a seething demonstration in Beirut.

Nasrallah's statement is deeply significant. For the first time, the Iran-aligned Hizbullah leader appeared to be calling for an open revolt against an Arab government as part of the fight against Israel. His words followed a declaration, much noted in the Arab media, by Egyptian Muslim Brotherhood leader Muhammad Mahdi Akef, in which he expressed his solidarity with Iran, and his endorsement of Shi'ite expansion in the Arab and Islamic world.

The Egyptian government was not slow to respond to Nasrallah's apparent call for Egyptian citizens to rise up against it. Foreign Minister Aboul Gheit said that the Egyptian armed forces existed to defend Egypt. He added, addressing Nasrallah directly, that "if need be, they will also protect Egypt from people like you."

The prospect of Egypt's finding itself pilloried by pro-Iranian forces in the event of a clash between Israel and Hamas in Gaza was foreseen prior to the operation. Arab countries aligned with the west have in the past quietly backed Israel in its confrontations with Iranian proxy forces. This time, because of the close proximity and the Egyptian control of Rafah, no such ambiguity was possible.

In the event, Egypt nevertheless made clear that it was prepared for the crossing to be opened to allow wounded Palestinians to leave for treatment and medical personnel to enter. Hamas demonstratively declined this offer. Egyptian sources have reported that a convoy of trucks and medical supplies was not allowed by Hamas to enter the Strip. Hamas personnel also prevented wounded Gazan civilians from crossing the border.

Hamas spokesman Fawzi Barhoum said that Hamas rejected the idea that only Palestinian 'corpses' should be permitted to leave. (Such actions and statements on the part of Hamas offer a useful reflection of the movement's and its allies' attitude toward their own civilians.) Hamas would like to use the southern border in order to bring in supplies (and, tacitly, weaponry) in case of an extended Israeli operation in Gaza, including the involvement of ground forces. Such a capacity could be of strategic importance to Hamas in determining the outcome of the present battle. Despite stormy demonstrations in Cairo and elsewhere, the Mubarak regime in Egypt has held out against these demands and is likely - with US encouragement - to continue to do so.

These latest events bring home the extent to which events in Gaza cannot be understood in isolation from the broader regional picture. Some analysts are maintaining that the Hamas escalation in Gaza which preceded the current operation was the result of a coordinated Iranian initiative.

Whether or not this claim has substance, it is a fact that the logic of Egyptian interests, plus Nasrallah's incendiary statements in Beirut, is serving as a kind of spotlight on the actual current strategic dispensation in the region - one which it is often convenient for Arab ruling elites to deny or blur.

It is likely that Hamas's accusations against Egypt - to the effect that Cairo was aware of an impending Israeli operation and took part in the deception preceding it - are largely correct.

At the same time, the desire to keep Egypt 'onside' may also play a role in limiting the dimensions of the current Israeli operation. Ultimately, the presence of an Iranian enclave between Egypt and Israel is a situation which neither country can accept. For the moment, however, all indications remain that the current operation is intended to bring about a renewed lull - probably through Egyptian mediation - rather than a mortal blow against the Hamas regime in Gaza.