If the White House was trying to fire a warning shot at the United States' "unshakeable" ally in the Middle East, it hit its target. Benjamin Netanyahu, Israel's prime minister, at the weekend responded defensively to President Barack Obama's suggestion that peace with the Palestinians depended on a return to pre-1967 borders.

"Israel is prepared to make generous compromises for peace," Mr Netanyahu said in Washington, but "it cannot go back to the 1967 lines. These lines are indefensible".

It was a stark rejection of any common ground for negotiations that have proceeded, in fits and starts, for nearly two decades. UN Resolution 242, which calls on Israel to withdraw from territory seized in the 1967 war, had been an outline for talks that Mr Netanyahu's predecessors accepted. Now, the Israeli prime minister is saying, Israel will unilaterally set its own borders - although it won't say what those borders are. So much for the "land for peace" model.

The US president deserves some credit for backing Mr Netanyahu into a corner, but Washington cannot be relied upon to keep up the pressure. Palestinians need to offer their own alternative to fill the void.

Israel has not offered a plan, but merely a rejection. That leaves it vulnerable to international pressure - never has its bad faith negotiations, delaying tactics abetting illegal land grabs, and lack of a realistic long-term solution been more apparent.

In the face of its intransigence, the only lever on Israel's behaviour is the moral argument, but it is an argument that almost every other country, besides the US, will understand. Isolation in the international community will sway hearts and minds; Israelis should come to the realisation that Mr Netanyahu is leading them nowhere.

First, Palestinians have to address their own internal divisions,as last month's reconciliation between Fatah and Hamas began to do. Hamas's leaders need to go further and denounce violence. Nothing could do more harm to the Palestinian cause than to justify Israel's security fears by shedding blood.

Then, a plan for statehood needs to be offered. The model, of course, is already there in the Arab Peace Initiative - it has been for a decade.

As the UN General Assembly nears a vote on recognising a Palestinian state, it is almost certain that a unified Palestinian front would carry the day.European countries, including Israel's key ally Germany, have made clear their frustration.

Mr Obama may be constrained by domestic politics, but Washington is no longer the only broker. At the weekend, Turkey's President Abdullah Gul called on Hamas to recognise Israel's right to exist. If Arab states did the same and offered guarantees of a permanent peace, it would expose Israel's claim to "defensible" borders as irrelevant. A secure Israel would be stripped of its last justification for draconian measures against Palestinians.

Mr Netanyahu will undoubtedly hold the party line for the rest of his US visit, but his statements have always been more about stall tactics than solutions. It is time the Palestinians offer their own clear plan, because it will be the only real plan on the table.