Obstacles to Middle East peace: Borders and settlements
The modern Israeli state was forged in the fires of the first Middle East war in 1948-1949, but from the beginning it was a state without clear borders.
The fact that complete, permanent borders still have not yet been drawn around Israel 60 years later is testimony to the rancour of its relations with neighbouring Arab states.
Jordan and Egypt have signed treaties with Israel, turning some of the 1949 ceasefire lines into state borders. But the absence of final settlements with Syria, Lebanon and the Palestinians mean most of Israel's boundaries remain potential flashpoints and the state itself is unstable.
In 1948, when British rule of Palestine ended, Israeli forces managed to push most of the Arab forces that joined the war to the former Mandate boundaries, which became temporary ceasefire lines.
The exceptions were what we now know as the West Bank, which remained under Jordanian control, and the Gaza Strip, which was controlled by Egypt.
Thus Israel came into being on 78% of the former Palestine, rather than the 55% allocated under the UN partition plan.
Parts of Israel's central region were just 15km (9 miles) wide, and strategic Jordanian-held territory overlooked the whole coastal region.
Fast forward to 1967, when Israel captured both the West Bank and Gaza Strip, as well as Syria's Golan Heights and Egypt's Sinai peninsula.
Israeli-controlled land now stretched from the Jordan Valley in the east and the Suez Canal to the west; it completely enclosed the Sea of Galilee in the north, and gave it a foothold on the Straits of Tiran in the Red Sea.
The Sinai was exchanged for peace with Egypt in the early 1980s (at about the time Israel occupied south Lebanon, where it remained until withdrawing unilaterally in May 2000).
So it was that, more than 30 years after the foundation of Jewish state, Israel acquired its first recognised international border with an Arab neighbour.
Jordan became the second treaty holder with Israel, agreeing river borders in the north and a demarcated desert border south of the Dead Sea.
The boundary between Jordan and the occupied West Bank was also agreed, but "without prejudice to the status of the territory".
Such deals are the exception, and the state of Israel and its neighbours have had to live with the insecurity of moveable boundaries and an assortment of different coloured lines ("green", "purple" and "blue").
Politically, the most important of the Green Lines - as the 1949 ceasefire lines were called - is the one dividing Israel from the West Bank and East Jerusalem.
Occupying the West Bank in 1967 was an important strategic gain in Israeli eyes, and successive governments have ignored the Green Line and built numerous Jewish settlements on the territory.
The settlements are illegal under international law, but Israel disputes this and has pressed ahead with its activity despite signing various agreements to curb settlement growth.
Today, more than 430,000 settlers live in the West Bank and East Jerusalem. Settlements have separate civil infrastructure to surrounding Palstinian areas and are protected by a vast military infrastructure.
The land is strategically significant, but in Judaism is also religiously and historically so.
The first settlers were religious Jews who remained in Hebron after celebrating Passover there in 1968.
The settlement movement has become closely affiliated to Jewish religious nationalism, which claims boundaries of modern Israel based on Genesis 15:18: "God made a covenant with Abram and said, 'To your descendants I give this land, from the river of Egypt to the great river, the Euphrates'."
On both political and religious grounds, therefore, it has been extremely sensitive for Israeli politicians to dabble in land-for-peace negotiations.
Prime Minister Yitzhak Rabin pushed for a two-state solution in the 1990s, and was made to pay for it with a Jewish nationalist assassin's bullet.
Successors Ehud Barak and Ariel Sharon unilaterally pulled out of south Lebanon and Gaza, respectively - both of which moves were followed by a resurgence of violent confrontation in subsequent years, discrediting that approach.
Benjamin Netanyahu managed to put the brakes on Rabin's historic drive for a two-state solution in the 1990s and has been in no rush to get to the negotiating table during his second term.
From the Arab viewpoint, the mininum acceptable territorial solution for a Palestinian-Israeli settlement is complete withdrawal from all the land occupied in 1967.
Saudi Arabia has proposed such a formula in return for Israel gaining normal diplomatic relations with all Arab countries.
Israel has sought to ring-fence East Jerusalem from any territorial retreat, and it hopes to annex the largest settlement blocs on the east side of the Green Line, which house a large majority of settlers.
This would involve adjustments to the Green Line, perhaps involving Israel swapping its territory for the settlements Ariel, Modiin Illit, Maale Adumim, Gush Etzion, etc.
Removing thousands of hardline settlers from other smaller, more isolated outposts would be a difficult task, however, even for the most secure of Israeli governments.
Further territorial compromises (having already been squeezed into 22% of pre-1948 Palestine) could also be a bitter pill for the Palestinian faction that favours a two-state solution, the Fatah party led by Mahmoud Abbas.
Not all Palestinians, however, want a two-state solution.
Hamas, which won the 2006 Palestinian parliamentary election and holds sway in Gaza, wants to avoid at all costs a negotiated deal with Israel that involves drawing permanent borders along the Green Line. Its wider aim is to establish a single, Islamic state within the whole of pre-1948 Palestine.
It believes such a state, with the return of 1948 refugees, would have an impregnable and growing Arab, Muslim majority, and would spell the end of Israel as a Jewish state.
In the long term, therefore, Israel's reluctance to accept the existing Green Line in some ways plays into the hands of militant Islamist groups such as Hamas.