Israel says it wants to stop rocket attacks from Gaza
By Jeremy Bowen
Middle East editor, BBC News
Now that Israel and Hamas are in what the Israeli defence minister Ehud Barak called "war to the bitter end" let's look at some of their options.
First of all, is it really a war to the bitter end?
It might be, and it might get a lot worse. Once a war starts, it is not easy to control.
But it is a fair guess that they will fight until there is some sort of diplomatic intervention that both sides can accept, or at least be in no position to refuse.
Israeli generals always assume that two clocks start when they go into action.
The first shows the time they need to achieve their military objectives.
The second shows the amount of time left before international pressure for a ceasefire becomes impossible to resist.
The diplomatic clock speeds up with the number of deaths, of civilians especially. With so many Palestinians dead already, the clock is ticking loudly.
Hamas is a less conventional organisation.
Its leaders realise that their reputation rests on their ideology of resistance.
Israel's actions have prompted protests around the world
The more pain they absorb, and the more they fight on, the more their stock rises among their supporters around the Middle East.
In a region full of anger against Israel and its western allies, Hamas will not want to accept anything that restricts what they see as their right to fight.
It will want to send out a message that it is not intimidated and it will fight for all those in this part of the world who are full of rage about the actions of Israel, and what they see as the complicity of its western allies.
Even so, the leadership of Hamas is shrewd.
It might accept a deal that leaves it with more international recognition, and gives a respite to its forces.
But for now Israel is still executing its plan. It is trying to control events.
And it is getting protection from the Bush administration, still riding diplomatic shotgun in its final month, saying that a ceasefire is desirable, but only when Hamas stops firing.
While the fighting goes on, Israel has many more options than Hamas.
It has powerful, modern armed forces. That does not mean that a standard military victory is assured. If it was, Israel would have gone to war before now.
The war in Gaza, like so many conflicts in the world today, is a fight between the strong and the weak.
Strategists call it asymmetric warfare.
In wars like this the weak side knows it has no chance of defeating the strong one in a stand-up, knock-down fight.
So, it uses what it can to magnify the power that it has, and to concentrate it on what it perceives to be a soft spot.
The most extreme example of that is the devastating blow delivered by the small group of hijackers who flew airliners into the World Trade Center in New York on 11 September, 2001.
Hamas will want to hit Israel as hard as possible, and has threatened to use suicide bombers as well as rockets.
But it will also want to turn Israel's own blows back against it.
Since the international pressure on Israel is being fuelled by the number of Palestinians it has killed in its air strikes, one way is to concentrate on the media battleground.
Israel has banned international journalists from entering Gaza
It matters a great deal in asymmetric warfare.
Winning the media battle in a world of non-stop, instant communication is a big part of winning the war.
When the American general Wesley Clark commanded Nato forces in Kosovo in 1999 he kept the television in his office tuned to 24-hour news.
Israel has, for the moment, banned international journalists from entering Gaza.
It has also declared much of the area on the Israeli side of Gaza's border wire a closed military zone, which among other things gives soldiers the power to order news teams out.
Israeli spokespeople around the world are sticking to some very consistent lines.
They repeat endlessly that Israel is acting in self defence, that its sovereign territory has been violated by rocket attacks, and that any country in its position would have done the same as it has done.
Apart from the defence minister's words about war to the bitter end, there seems to have been a conscious effort to keep the level of rhetoric down.
The opposite happened during the 2006 Lebanon war, saddling Israel with a vision of victory that it had no chance of achieving.
But Israel also wants to send another set of messages.
It is attacking symbols of Hamas power and prestige, like the Islamic University in Gaza.
As the number of Palestinians injured and killed increases, so does pressure on Israel
It believes it can reduce the position of Hamas so severely that it will not be able to launch any more rockets over the border.
The Israelis think that one way they'll do that will be to separate the Hamas leadership and core support from the great mass of Palestinians in Gaza, by showing them the cost of Hamas actions.
It is unlikely that will happen.
For Palestinians, whatever Israel says about pinpoint attacks, this feels like an assault on everyone.
Large numbers of civilians, including children, have been killed. The police recruits Israel killed at their passing out parade will have included many young men who joined up simply to get a decent job, which is a rarity in Gaza.
But for Israel, this is about more than simply beating Hamas.
It wants also to expunge the black mark against the Israeli army's competence that has been there since it was fought to a standstill by Lebanese Hezbollah in 2006.
The Israelis call that restoring the army's deterrent power. That means they want any would-be enemies to be very scared about what they are prepared to do.