The histories of many lands have repeatedly demonstrated two patterns in the relationship of extremism to political and economic conditions. One is that the combination of miserable economic circumstances and a lack of peaceful political channels for pursuing grievances tends to gravitate people toward extremist groups and ideologies. The second is that the resulting extremism is on a sliding scale. What may have been seen at one time as an extreme response to circumstances may, as misery continues and possibly worsens, come to be seen as part of an inadequate status quo and is eclipsed by something even more extreme.

Such a process is taking place today in the Gaza Strip, the open air prison in which 1.8 million people endure what for some time have been genuinely miserable circumstances. Blockade by Israel, aided to varying degrees by Egypt and punctuated by repeated Israeli military assaults, has destroyed much of the Gazan economy and kept residents in squalor. The estimated unemployment rate is around 44 percent, and the Strip is still strewn with rubble from the most recent Israeli assault last year, with lack of materials and other impediments permitting only minimal reconstruction so far.

An unsurprising result is growth in the number and activity of Gaza-based extremists—specifically and most recently ones claiming allegiance to the so-called Islamic State or ISIS. Their numbers have increased, according to an estimate by Nathan Thrall of the International Crisis Group, from several hundred a few years ago to a few thousand today. They act in opposition not only to Israel but also to Hamas, the group that tries to function as a governing authority in Gaza and is to the extremists a part of a despised status quo. “We will stay like a thorn in the throat of Hamas, and a thorn in the throat of Israel,” says a spokesman for groups that identify with ISIS.

The ill consequences of this rise of extremists in the Gaza Strip go beyond the undesirability of any expansion of the ISIS brand and ISIS influence. The extremists from time to time fire rockets into Israel despite the efforts of Hamas to stop such firings. The rockets endanger innocent citizens of Israel and also, given the Israeli government's pattern of blaming Hamas for anything that goes on in the Strip and striking back with force, carries the risk of precipitating the next Gaza war. The Gaza extremists, especially if they link up in any way with their ideological soulmates in the Sinai, also may stop a modest thawing in relations between Hamas and Egypt, which recently has slightly relaxed closure of its part of Gaza's borders. (Abdel Fattah el-Sisi's Egypt, by the way, is another prime exhibit of how repression and denial of political rights foster the growth of extremism and terrorist violence.)

Israel's suffocating blockade is very hard to explain, much less justify, even if one gets beyond the huge moral issue raised by inflicting such deprivation on 1.8 million people and uses as a frame of reference the narrow objectives of the right-wing Israeli government. The situation does help make possible the propaganda point, often invoked by that government and its supporters as an excuse for continuing to occupy the West Bank, that when Israel “withdrew” from the Gaza Strip the response supposedly was rocket fire and the Palestinians making a hash of things. No mention is made, of course, of how Israel has done everything it can to make the Gaza Strip ungovernable. And by branding Hamas as an irredeemable extremist group, there is a further propaganda point that the Palestinian Authority is getting in bed with “terrorists” any time it tries to achieve reconciliation with Hamas in the interests of Palestinian unity. No mention is made of how Hamas, which won the last free all-Palestinian election, has made it clear that if a Palestinian state is created it is prepared to observe an indefinite long-term cease-fire with Israel.

Destruction of Hamas seems to be a purpose of the blockade and military assaults, with the idea being that if ordinary Gazans suffer enough they will blame Hamas and withdraw support from it. But if that is the purpose, the policy has been a failure. The longer the policy goes on the more it starts to look like the failed half-century effort by the United States to use an embargo of Cuba to try to get rid of the Castro regime—with the difference that Israel has a much greater stranglehold on the Gaza Strip, and the suffering it has exacted on the targeted population has been much more severe.

Even if Israel could somehow kill off Hamas with this strategy, the increase of the ISIS-types in Gaza points to the last flaw in the strategy. If Hamas were to go, the replacement probably would be something that everyone ought to consider much worse. It is a further question whether the Israeli government recognizes this, and whether even if it does, it would nevertheless continue its self-destructive policies in its single-minded determination to destroy a two-state solution to the Israeli-Palestinian conflict.