There is no such thing as a legal Israeli settlement on the West Bank. Under international law there should have been no building in any of the occupied territories. Yet Israel has carried on constructing, often strategically, chains of settlements as around occupied East Jerusalem, in defiance of UN rulings. A halt to new settlement activity and to the expansion of existing sites has been pivotal to all recent efforts to advance the peace process.

Successive Israeli governments have equivocated on the issue. They have often claimed that new work is only “in-filling,” have asserted that by their rules at least, such settlement activity is legal and have denied — against all logic — that any Palestinian land has been seized.

Now thanks to a government document found and leaked to a newspaper by an Israeli human rights activist, it appears that Israel has been regularly flouting even its own regulations on settlements. Of the 220 Israeli communities built in the West Bank, 120 were actually authorized by the authorities. The leaked report shows that fully 75 percent of these have been constructed either without the right permit or in contravention of permits that were granted. Not only that, but in 30 settlements, schools, synagogues and police stations have actually been built on land that still belongs to Palestinians who naturally were not consulted beforehand.

None of this of course surprises close observers of Israeli behavior in the occupied territories for the past 40 years. We have become used to Israel’s double-speak and — frustratingly — used also to the way in which the outside world has bought the fictitious picture of a plucky, beleaguered little country facing down its malevolent Arab neighbors.

But the enormity of Israeli behavior in Gaza has shocked world opinion. People are now remembering how in 2007, before it launched its assault on Hezbollah in southern Lebanon, Israel sent its jets and warships to deliberately destroy key civilian infrastructure throughout the country. This had nothing to do with Hezbollah. It was merely a vicious communal punishment. In Gaza, Israel descended even lower.

Moreover, it is not simply the phoney image of Israel as the brave little guy that is beginning to suffer these days. As this week’s leaked documents on illegal settlements make clear, Israel is starting to lose the credibility war as well. It may seem extraordinary that after its spies stole weapons secrets from its principal ally, the United States, and after its jets sank US warships, Washington has not doubted Israeli motives. But tolerating such behavior could be discounted as realpolitik.

When, however, a country acquires a wider reputation for untrustworthiness, the impact can be longer lasting and more corrosive. The Obama White House knows Washington is not trusted in the Middle East because of its past hypocritical support for Israel. If, in American and European eyes, Israel is now seen as untrustworthy, it may be harder for governments to resist clear public pressure to drive Israel by economic means toward confronting its lies and fabrications and taking real steps toward a just Palestinian settlement.