17 November 2012 Last updated at 09:31 ET

Gaza a dangerous crisis for turbulent Middle East

By Jeremy Bowen BBC Middle East editor

Israel has moved troops to the border and authorised the mobilisation of up to 75,000 reservists

Last weekend it was looking as if the latest round of violence between Hamas and the Israelis was losing impetus.

Both sides were blaming each other for starting it and, by Monday, there was talk of a ceasefire brokered by Egypt.

But a dramatic flare-up was transformed into an increasingly serious international crisis by Israel's assassination of Ahmed Jabari, the leader of Hamas's military wing, and by everything that has followed.

This crisis is especially dangerous because the Middle East is more turbulent and less stable than at any time since the 1950s.

Convulsive changes

The old certainties and some of the old faces have gone.

Just look round the borders of Israel and the Palestinian Territories.

Syria is deep in a civil war. Lebanon has so many connections with Syria that it can't help but be involved.

In Jordan, demonstrators are chanting the slogan they used in Tunisia, Egypt, Libya, Syria and all the other places - the people want the fall of the regime.

And Egypt no longer has President Hosni Mubarak, the man that the Americans and the Israelis relied on at moments like this, to uphold the status quo.

He is serving life for his part in the killing of demonstrators.

His democratically elected successor, Mohammed Mursi, is also a leader of the Muslim Brotherhood - the Egyptian group that pioneered and spread the idea of political Islam.

Its offshoots include Hamas, for which Egypt has expressed strong support, though so far that has not gone much beyond rhetoric.

And Turkey is seconding Egypt. Behind the scenes, they will both be pushing for a ceasefire, but their support will give Hamas the confidence, if necessary, to carry on.

The convulsive changes in the Arab World in the past two years pushed the conflict between Israel and the Palestinians out of the headlines.

But it never went away, and with much of the rest of the world distracted, it had been getting sharper.

A violent crisis, even a new war, was the closest thing to a certainty that existed in Middle Eastern politics.

Israel has authorised the mobilisation of up to 75,000 army reservists; Hamas is trying to land a heavy punch sending missiles towards Tel Aviv and the Israeli side of Jerusalem.

So far what is happening is nowhere near the scale of the war between Hamas and Israel either side of the New Year in 2009.

But if the plaintive calls for what the Americans and British are calling de-escalation continue to be ignored by both sides, it could go the same way.