he Bush administration is driving American credibility as a Middle East peacemaker to a new low with its support for a major expansion of Israeli settlements in the occupied West Bank. While designed to provide a short-term boost to Israel's embattled prime minister, Ariel Sharon, this cynical change in administration policy will have important long-term costs. It will further demoralize Israeli and Palestinian moderates, frustrate Washington's closest European and Middle Eastern allies, and undermine the American-backed road map peace plan, which, though a long shot, is the only current peaceful political alternative.

Last week Mr. Sharon issued tenders for the first 1,001 of a planned 1,634 heavily subsidized new apartments in existing West Bank settlements. Israel has long contended that expanding existing settlements, which it calls "natural growth," somehow does not violate the road map's call for a freeze on all settlement activity, even though the road map specifically excludes this form of expansion. "Natural growth" has accounted for most of the nearly 100,000 additional West Bank settlers since 1992, a near doubling of the settler population there. Most of these, including the latest group, have been attracted by huge government subsidies. Yesterday Israel announced it was rezoning land for a further 533 new settler homes on the outskirts of Jerusalem.

Settlements are such a sensitive matter because they cut directly to the core of the Israeli-Palestinian issue - the ultimate division of the land of Palestine. To be just, workable and sustainable, any peace plan will have to divide that land into two coherent territories that are defensible and economically viable. The presence of more than 250,000 Israeli settlers scattered across the occupied West Bank, Gaza Strip and Golan Heights, leaving aside the added complications of East Jerusalem, make that division immeasurably harder. Every new increase, "natural" or otherwise, adds to the challenge. No one step by Israel would be likely to do more to restart peace talks and isolate Palestinian terrorists than announcing a genuine freeze on all settlement construction.

No recent administration has been less engaged in the pursuit of Middle East peace than the Bush administration. Now it seems to be sliding from dangerous passivity to outright obstruction.