This week, the Palestinians will petition the U.N. Security Council for admission as a full member state. Admitting Palestine would be a nightmare for Israel and a serious problem for the United States. Nonetheless, President Barack Obama made the wrong decision in declaring Wednesday that the U.S. will oppose the Palestinians' bid for statehood.

Admitting Palestine as a full member state of the U.N. threatens Israel because it means that Israel's military forces stationed over the "Green Line" that separates the two entities will be an army occupying an internationally recognized, sovereign state. As such, Palestine will be well within its rights to petition the Security Council for a Chapter 7 resolution that calls on Israel to dismantle all settlements and remove all troops. Such a decision is an enforceable action, much as the decision to use forces under a U.N. mandate to repel North Korea's attack on South Korea in June 1950 or, to push Iraq out of Kuwait during the Persian Gulf War.

Such a decision could conceivably justify an armed attack on Israel. While the U.S. is very likely to veto any such resolution, lesser resolutions — such as one calling for economic sanctions of Israel until it removes settlers and troops from Palestine — would be harder for the U.S. to veto.

The United States is now pinned on the horns of a dilemma. If it vetoes Palestinian requests for full statehood, it will find itself thwarting the bid for self-determination of an Arab people following so soon after our missteps on Iraq have tarnished our reputation as a force for liberty. America's long-term support for the leaders so recently overthrown in Tunisia and Egypt has not made it popular in the Arab world. Nor, of course, has its stalwart support of Israel, which has long been seen to be at the expense of the legitimate aspirations and rights of the Palestinians.

If the United States votes in favor of Palestinian statehood, it runs the risk that Israel will feel so deeply betrayed that it will become increasingly isolationist. When Israel has felt such isolation before, such as when France withdrew its patronage of Israel in the lead-up to the 1967 war, the move heightened Israel's sense of panic and fear and resulted in a war that changed the face of the Middle East so drastically that this week's events at the U.N. are a direct result.

Now is not a great time to leave Israel feeling abandoned. Israel's relationship with its previously staunch regional ally Turkey is in tatters. The commitment of the new authorities in Cairo to the Camp David Accords, on which Israel relies to minimize the risk of large-scale conventional war, is open to question. And the menace of Iran's nuclear programs shimmers dangerously on the horizon. Apart from Israel's nuclear arsenal, U.S. support is the last remaining pillar of certainty that Israel depends on to feel safe.

Nevertheless, the case for Palestinian statehood is compelling. History will not judge the U.S. favorably if it stands in the way of an idea whose time has more than come. Nor do America's short- and medium-term strategic interests benefit from being seen as opposing the right to self-rule of Arab peoples. In the wake of Iraq and our mixed response to the Arab Spring — where America stood on the sidelines for too long in Egypt, Saudi Arabia, Bahrain and Syria — America must now show Arab people that we are on their side. Voting in favor of Palestinian independence, especially in defiance of Israel's wishes, is the clearest possible statement of that.

Mr. Obama's speech Wednesday need not be the final word. He should reconsider and offer America's vote in favor of Palestinian statehood, balanced by three other moves:

•The U.S. should make clear that it will veto any move to impose economic or military sanctions on Israel for the presence of existing settlements and troop deployments in Palestine until Jan. 1, 2021. This gives Israel and Palestine nearly a decade to resolve these issues in direct negotiations, while preserving the threat that if they do not, the U.S. will not be obligated to stop the U.N. from taking action.

•The U.S. should move its embassy from Tel Aviv to West Jerusalem. Admitting Palestine to the U.N. with the 1967 boundaries means, de facto, that America is likewise recognizing West Jerusalem as a part of Israel now and forever. Having the U.S. embassy there should be seen as the gesture of evenhandedness.

•Congress should pledge to continue its direct military support of Israel, at current levels, until Jan. 1, 2021. Knowing that the sharp edge of Israel's sword will not be blunted during this time of transition is a key dimension of sweetening what we know to be a bitter pill.

The dream of a directly negotiated peace between Israel and the Palestinians is dim. This move, entered into under duress, may be the unexpected path that leads all sides out of the thicket. We can certainly hope so.

Ariel Ilan Roth is the director of Global Security Studies at the Johns Hopkins University, Krieger School of Arts and Sciences. His email is ariel.roth@gmail.com.