We have seen this movie before. In the summer of 2006, Israel invaded Lebanon. Replace "Hizbullah" with "Hamas" and "Lebanon" with "Gaza," and much we have seen in the last few days is depressingly familiar. Once again, the Israeli military assault is justified on the basis of the need to stop rocket attacks on Israel, even though it is widely conceded that this will not be the result. Once again, establishment voices in Washington give carte blanche to the military action, even though few believe it will accomplish its stated objectives, and everyone understands that it will impose a huge political cost for the United States around the world, especially in the Arab and Muslim world.

But, although one can only be sick at the repeated, completely unnecessary loss of life, there is a silver lining to the Lebanon precedent: international outrage in 2006 effectively forced the United States government into a corner, in which it finally could no longer resist a ceasefire. And there is no reason to believe that what happened in 2006 can not and will not happen again now.

The question is then how long it will take international outrage to build to the level necessary to force the US government to stop backing the Israeli military action, and therefore how many Palestinians and Israelis will needlessly die in the meantime.

In some ways we have a head start over 2006. No-one can now plausibly claim that there is something intrinsically wrong with a ceasefire, or that there is something intrinsically wrong with negotiating with Hamas to achieve a new ceasefire. After all, just over six months ago, Israel and Hamas negotiated a ceasefire, brokered by Egypt, with the active encouragement of the United States. There was never any daylight between Israel and Hamas on whether a ceasefire was desirable; what was in dispute, and remained in dispute, was what the parameters of the ceasefire would be. Israel wanted the ceasefire limited to military calm-for-calm across the Israel-Gaza border. Hamas wanted the ceasefire to include significant easing of the economic blockade on Gaza and also to extend to the West Bank. These differences were finessed in the ceasefire agreement at the time, leading many to conclude that the disagreements would eventually explode the ceasefire agreement, as they now have.

But if you know this history, then you know that the statement "Israel had to act to protect its citizens from rocket attacks" is sorely lacking. Of course Hamas rocket attacks generated political pressure in Israel for a response. But was this the only possible response? If it was not the only possible response, was it the most effective response towards the stated goal? Among possible responses, was it moral and just?

After all, there is every reason to believe that the ceasefire could have continued and even been strengthened if Israel - and the United States - had been willing to ease the economic blockade of Gaza and extend the ceasefire to the West Bank. Since it was at least as likely - probably much more likely - that this would have done more to reduce and perhaps eliminate rocket attacks, it is reasonable to suggest that a key goal of the military assault is to maintain the economic blockade and maintain the status quo in the West Bank.

And, when you consider that former President Carter and other luminaries have denounced the economic blockade as an "abomination," and that even Israeli Prime Minister Olmert has conceded that Israel must give up almost all of the West Bank in any political settlement, then it is extremely hard to justify the military campaign on the basis that it is necessary to defend the economic blockade, or the status quo in the West Bank.

And therefore it is likely that pressure can build more quickly now than it did in 2006, and fewer people will have to die. Already, "mainstream pro-Israel peace groups" in the US have spoken out in favor of an immediate ceasefire. Notably, J Street called not only for a ceasefire, but for lifting the blockade.

There are many ways to take action; you can write to President-elect Obama here and to President Bush and Congress here.