The two-state solution would establish an independent Palestinian state alongside Israel — two states for two peoples. In theory, this would win Israel security and allow it to retain a Jewish demographic majority (letting the country remain Jewish and democratic) while granting the Palestinians a state.

Most governments and world bodies have set achievement of the two-state solution as official policy, including the United States, the United Nations, the Palestinian Authority and Israel. This goal has been the basis of peace talks for decades.

Why is the solution so difficult to achieve?

There are four issues that have proved most challenging. Each comes down to a set of bedrock demands between the two sides that, in execution, often appear to be mutually exclusive.

1. Borders: There is no consensus about precisely where to draw the line. Generally, most believe the border would follow the lines before the Arab-Israeli war of 1967, but with Israel keeping some of the land where it has built settlements and in exchange providing other land to the Palestinians to compensate. Israel has constructed barriers along and within the West Bank that many analysts worry create a de facto border, and it has built settlements in the West Bank that will make it difficult to establish that land as part of an independent Palestine. As time goes on, settlements grow, theoretically making any future Palestinian state smaller and possibly breaking it up into noncontiguous pieces.

2. Jerusalem: Both sides claim Jerusalem as their capital and consider it a center of religious worship and cultural heritage. The two-state solution typically calls for dividing it into an Israeli West and a Palestinian East, but it is not easy to draw the line — Jewish, Muslim and Christian holy sites are on top of one another. Israel has declared Jerusalem its “undivided capital,” effectively annexing its eastern half, and has built up construction that entrenches Israeli control of the city.