From the earliest days of the peace process, it was clear that Israel's settlements would be one of the most contentious issues on the Israeli-Palestinian and Israeli domestic agendas. Conventional wisdom has held that serious Israeli action on settlements must be put off until a deal is ready to be signed. This is based on the logic that given the huge amount of political capital it will cost any Israeli government either to freeze settlements or to pursue peace, no Israeli government can do both at the same time. This logic has been advanced in Israel and in Washington since the time of Yitzhak Rabin, and has been largely accepted by every U.S. government since George H.W. Bush.

But such logic is a dangerous trap. Far from smoothing the path to peace, these settlements' continued expansion directly undermines any chance of reaching a peace agreement. We say this with conviction born of experience from 15 years of peace efforts.

Why? Because it emboldens settlers and their advocates, who are more than happy to play the various political parties off each other, creating an incentive for Israeli governments to indulge their demands.

Why? Because settlement expansion further complicates the situation on the ground, making it even more difficult to eventually "unscramble the egg" and establish a viable Palestinian state living side-by-side with Israel.

Why? Because every new house, plan, and approval deals a body blow to the credibility of peace efforts and undermines pro-peace Palestinian leaders; Palestinians interpret these moves as indications that Israel is not serious about peace.

If the Obama administration's Middle East peace efforts are to be credible, let alone successful, President Obama and his officials must not fall into this same trap. They must recognize that a comprehensive settlement freeze needs to be the starting point, not the ending point, of its peace efforts.

This means no longer accepting rationalizations and procrastination tactics on the issue. It means refusing to get pulled into endless, artificial debates about what "expanding a settlement" actually means - debates whose clear purpose is to delay, water down, or scuttle any settlement freeze.

It means not buying arguments about settlements needing to expand to accommodate "natural growth," bearing in mind that growth in settlements is not "natural" in any way, but is the result of government policies designed to attract Israelis to settlements and keep them there.

It means rejecting efforts to create special categories of settlements that Israel wants to continue to expand - like those in the ever-expanding, unofficial "settlement blocs." It means adopting a policy that is predicated on the clear recognition that any settlement expansion directly threatens the prospects for ever achieving a negotiated Israeli-Palestinian agreement - including an agreement under which Israel could receive recognized, permanent claim to some of the settlements it holds most dear.

It means laying down a clear red line: no settlement expansion of any kind, period. It means no new settlement construction or planning, a freeze on construction and plans that are in the pipeline, a freeze on projects that are already proceeding (and compensation, as necessary, for investors and developers), and the cancellation of policies that encourage Israelis to move to settlements.

The government of Israel has the power to enforce such a freeze. Israeli planning and construction in the West Bank - an area that Israel has never annexed - are not treated as merely technical or bureaucratic matters under Israeli law. Rather, the government of Israel recognizes that such activities have special political, security and diplomatic significance. As a result, all settlement planning and construction require the direct approval of the political echelons of the Israeli government - primarily the Minister of Defense and sometimes the entire cabinet.

The government of Israel has the power to freeze settlements completely. Whether it does so is strictly a question of political will, not legal authority.

In 1993, at the outset of the peace process, then-Prime Minister Yitzhak Rabin asserted that Israel must "continue the peace process as If there is no terror, and fight terror as if there is no peace process." He was certainly right in this view.

However, the similar view on settlements - the view that says that Israel can "negotiate peace as if there is no settlement expansion and expand settlements as if there are no peace negotiations" - is dangerously wrong. It is a dangerous trap that President Obama must avoid. .