SOMETHING SURPRISING happened Tuesday in a Middle East diplomatic landscape that most people assumed was frozen over: Israeli and Palestinian negotiators met face-to-face for the first time in 16 months. That they did so was partly to the credit of Jordan’s King Abdullah, who has been working feverishly to restart negotiations, and partly to the credit of the “Quartet,” the diplomatic amalgam of the United States, the European Union, Russia and the United Nations, which has been pressuring the two sides for months.

Encouragingly, the session ended with an agreement to continue the low-level contact. Unfortunately, the odds remain high against real movement by Israeli Prime Minister Benjamin Netanyahu and Palestinian President Mahmoud Abbas toward a peace deal. At worst, Tuesday’s session could be the kickoff to a season in which Palestinian and Israeli leaders do their best to isolate, sanction and punish each other — at the expense of their own people and their own long-term interests.

Mr. Abbas dispatched his negotiator to Tuesday’s meeting to avoid being blamed by the Quartet for causing the stillbirth of its latest peace plan. But his disinterest in dealing with Mr. Netanyahu is manifest in his continuing preconditions for formal negotiations, including a freeze on all Israeli settlement construction in the West Bank and Jerusalem.

The Palestinian leadership says it is merely waiting for Jan. 26, which according to its interpretation of the Quartet plan is a deadline for each side to submit proposals on the borders and security of a future Palestinian state. Israel, for its part, is still waiting for Palestinians to meet the Quartet’s requirement of unconditional negotiations. At best, the informal talks could be a way around this impasse. Mr. Netanyahu could help by matching the Palestinian proposal with one of his own.

If he doesn’t, the Palestinian Authority will probably renew a self-defeating international diplomatic offensive against Israel that so far has seen Palestine win admission to the international cultural agency UNESCO (at the crippling expense of its U.S. funding) and unsuccessfully petition the U.N. Security Council for full U.N. membership. Mr. Abbas’s next steps reportedly could include another attempt to have the Security Council censure Israel’s settlement construction, which would succeed only in embarrassing the Obama administration.

More significantly, Mr. Abbas’s secular Fatah movement may finally proceed with a long-promised, if likely superficial, reconciliation with the Islamic Hamas movement. Since Hamas still refuses to recognize Israel, this would definitively end the possibility of negotiations and prompt a cutoff of U.S. funding for the Palestinian Authority. But Mr. Abbas, who at 76 has pledged to retire this year and seeks a legacy, could claim to have achieved Palestinian “unity,” even if it retards statehood.

For his part, Mr. Netanyahu has done nothing to encourage a Palestinian shift toward negotiation. On the contrary, Israel recently moved ahead on thousands of new housing units in the settlements around Jerusalem. Limited by his own right-wing coalition, by his poor relations with the Obama administration, by his distrust of Mr. Abbas and by his apprehension about the consequences for Israel of the Arab Spring, Mr. Netanyahu shows no inclination to take risks for peace. In the short term, that may make sense; in the longer run, Israelis, like Palestinians, stand to lose.