It’s official: forget Cairo. Fold up the speech and throw it in the bin, or put it in that already bulging folder marked “Bad Faith & Broken Promises”.

That seems to be the unintended but unavoidably obvious message of the about-face by the US president Barack Obama and his decision last weekend to press ahead with Israeli-Palestinian talks despite Arab and Palestinian demands that Israel halt West Bank settlement construction first.

Interestingly, Mr Obama did not make the announcement himself. He put his travelling secretary of state, Hillary Clinton, up to it during a stop in Jerusalem on Saturday.

But make no mistake: the onus for the decision falls on Mr Obama himself. And in its vindication of violence over diplomacy and stalling over engagement, Mr Obama’s move ranked him alongside George W Bush, the man whose record he ran against to win the presidency.

It was Mr Bush who, in April 2004, endorsed Israel’s claim to parts of the West Bank seized in the 1967 Middle East War, a comparable victory for Israel’s policy of coercion over real negotiation.

Yet Mr Obama’s move is arguably more objectionable and, for those who supported him, far more deflating. By the time Mr Bush took the podium at the White House with Ariel Sharon, the Israeli prime minister grinning at his side, to declare certain West Bank settlements permanent, there were few remaining illusions about what the US president was and what he stood for.

By then, in particular, the existence of weapons of mass destruction in Iraq as Mr Bush’s main pretext for invading that nation had been exposed as a sham.

Mr Obama was said to be different, and his Cairo speech gave Arabs and Muslims throughout the world a reason to think so. After all, it was in the Egyptian capital that the US leader declared in June to thunderous applause: “The situation for the Palestinian people is intolerable. And America will not turn our backs on the legitimate Palestinian aspiration for dignity, opportunity, and a state of their own.”

On Saturday, the US made a show of appearing to do precisely that.

At the news conference in Jerusalem where Washington unqualifiedly dropped the settlement precondition requirement, Mrs Clinton and the Israeli prime minister Benjamin Netanyahu donned the shoes of Mr Bush and Mr Sharon.

It was not so much the ensuing dissembling that was discouraging – after all, we have grown accustomed to the evasions and lying that are rife on all sides of the Israeli-Palestinian conflict – but the brazenness of it that disheartened any listener who held out hope that this US administration would turn over a new leaf with Palestinians in particular, and the Arab world in general.

Here was Mr Netanyahu: “Now there has not been, not in the last 16 years – not 40 years, but 16 years – since the beginning of the peace negotiations between Israel and the Palestinians any demand ever put, not on restraint, but on any limitation of settlement activity as a precondition for entering negotiations.”

And what was the US secretary of state’s reply to this technically true but wildly misleading statement about Israel’s commitment to a just and lasting peace for the Palestinians? Like the trained lawyer she is, Mrs Clinton replied: “I would add just for context that what the prime minister is saying is historically accurate.”

The secretary of state’s carefully parsed answer recalled the observation of a former Middle East negotiator, Aaron David Miller: “I’m not a lawyer by training, but I know one when I see one. For far too long, many American officials involved in Arab-Israeli peacemaking, myself included, have acted as Israel’s attorney, catering and co-ordinating with the Israelis at the expense of successful peace negotiations.”

Did Mr Netanyahu reward US surrender with conciliation? Hardly. The next day a mocking, strutting Netanyahu talked about Palestinians the way one would talk, say, about an out-of-control, delusional child. He told his cabinet that he hoped that Palestinians would “get a grip” and get on with talks.

There was no immediate public reaction from Arab capitals to Washington’s reversal, implying either that Arab governments were stunned into silence or that they expected this all along and did little to prevent it. But the turn-round will have far-reaching consequences.

For one thing, one would be hard pressed to imagine what more could be done to undermine the tattered credibility among Palestinians of the so-called “moderate” president, Mahmoud Abbas.

For another, champions of “moderation” both in the region and elsewhere will have even less to show the next time young Arabs, let alone young Palestinians, demand illustrations of its benefits.

We will doubtlessly learn in coming days of the behind-the-scenes wrangling that led to Saturday’s announcement. Consider this scenario: as Mr Obama prepares to receive the Nobel Peace Prize in Oslo next month and his speechwriters get busy preparing his acceptance speech, it surely must have dawned on the White House that the president was in need of some real accomplishments to buttress his widely admired skills as an orator.

Aware that many have questioned his qualifications for the prize and at the same time eager to earn it, Mr Obama bought into the chimera of the Israeli-Palestinian “peace process” at the expense of real steps towards peace.