Powerful demographic, cultural, and strategic currents in Israel and the United States are driving the two countries apart. In America, the once-solid pro-Israel consensus is being corroded by partisan rancor, which also pits conservative Jews against the more liberal Jewish majority. In Israel, surveys of young Jewish citizens reveal a disdain for democracy, and, in some cases, a readiness to curb the civil liberties of non-Jews. Prospects for preserving a liberal Zionism against the pressures for "Greater Israel" are dimming as hopes for a two-state solution fade.

The acrimony between President Barack Obama and Prime Minister Benjamin Netanyahu has been a symptom, not cause, of the deeper crisis. If the alliance becomes just a transactional arrangement, then the moral, emotional, and largely intangible bonds that have long tied the two countries together will continue to weaken. Going separate ways at a time of Middle East chaos, and despite profound historical commitment, would be an immense tragedy. The partnership must restore the shared vision that created it.