During a swing through Washington this week, Israeli Prime Minister Benjamin Netanyahu repeatedly said his country's pre-1967 lines are "indefensible."
A total withdrawal from the West Bank, a strategic highland looming over central Israel, would certainly leave the Israeli heartland more vulnerable to attack or invasion. But some experts say that long-range missiles, weapons of mass destruction and cyber-warfare mean that in the modern world the greater risks lie elsewhere _ especially if a future Palestine is demilitarized.
The border issue is now at the heart of the latest tensions in Mideast peace efforts. Seeking to break an eight-month deadlock, President Barack Obama last week proposed that Israel commit to establishing a Palestinian state based on its frontiers before the 1967 Middle East war, when it captured the West Bank, east Jerusalem and Gaza Strip. The Palestinians claim all three areas for their state.
Israel withdrew unilaterally from Gaza in 2005. But Netanyahu says a similar pullout from the other areas, even as part of a negotiated peace deal, would jeopardize his country's security on a different scale.
A return to those lines would leave Israel with a waistline just nine miles (15 kilometers) wide at its narrowest point, Jerusalem surrounded on three sides by Palestinian land and the country's main international airport just a few miles (kilometers) away from the border. If hostilities break out, Israel's largest cities could be vulnerable to rocket fire and other attacks.
Yet experts note that Israel waged the 1967 war _ the most decisive military victory in its history _ from these same lines. And today, its overwhelming military superiority leaves it in a strong position to defend itself against any external threat.
"Geography only plays a limited role in war. What you really don't want is people who hate you on the other side," said Martin Van Creveld, a military historian at Hebrew University in Jerusalem.
He said Netanyahu's insistence that Israel maintain control of the Jordan Valley, a strategic area along the West Bank's eastern border with Jordan, would be better for Israeli security but is not "entirely necessary."
Even Obama doesn't expect a pullback to the exact 1967 lines. In a pair of speeches, he said a peace treaty should be "based on the 1967 lines with mutually agreed swaps."
The Palestinians have accepted this position. But they envision only tiny modifications to the former lines, and expect an equal amount of territory inside what is now Israel in return. Netanyahu has indicated this is unacceptable.
Still, two previous Israeli prime ministers _ Ehud Barak and Ehud Olmert _ offered the Palestinians peace treaties that would have included an Israeli withdrawal close to the 1967 border. A third, Ariel Sharon, considered the line "a reference point," according to his top aide, Dov Weisglass.
Former Israeli lawmaker Isaac Ben-Israel, a retired Israeli air force general, said the matter is therefore less about military considerations alone and more about policy and neighborly relations.
He noted that Holland and Belgium have "indefensible borders" and in the past have been susceptible to invasion. "But that doesn't matter now because they have no external enemy," he said.
He said the prime minister's approach to the borders conveys a pessimistic outlook that peace will not necessarily translate into a cessation of hostilities.
The public seems to agree with Netanyahu. According to a survey published Wednesday, 61 percent of Israelis oppose the formula of 1967 borders with land swaps as a basis for an agreement with the Palestinians, while only 27 percent favor it. The Geocartographia Institute's poll surveyed 500 Jewish Israelis and had a margin of error of four percentage points.
Giora Eiland, another retired general, says that Israel's security doctrine has never assumed that peace would bring quiet and that under these circumstances controlling land does matter.
While longer-range missiles can already reach all of Israel, he said a West Bank withdrawal could put the country's heartland _ Jerusalem, the airport and the Tel Aviv region _ in range of the short-range rockets and mortars that have made life miserable for those near Gaza.
He added that a demilitarized state, which the Palestinians say they would accept, would preclude the threat of tanks, artillery and fighter jets, but not be able to prevent smuggling of shoulder-mounted, anti-tank missiles. Hamas militants have brought these weapons into Gaza and used them against Israeli targets.
"You can't inspect these types of weapons and there is no effective way to stop them," said Eiland, a former Israeli national security adviser.
He said Israel would remain particularly vulnerable since most of the land swaps are expected to be devoted to annexing existing settlement blocs rather than holding on to key strategic points, such as areas outside Jerusalem or near Ben-Gurion airport.
"The bottom line is, these are very uncomfortable lines for us," he said.
Eiland, who stepped down as security adviser in 2006, said that in internal discussions at the time, Israeli officials spoke of 12 percent of the West Bank as the minimum Israel would have to hold on to secure its most basic security needs. During peace talks in 2008, Olmert proposed keeping about 6 percent, while the Palestinians proposed giving Israel just 1.9 percent.
Van Creveld, the military expert, countered that some of the settlement enclaves Israel wants to keep would actually make Israel's borders more indefensible.
"That West Bank would look like Swiss cheese and you can't defend Swiss cheese," he said. "The situation as it existed before '67 shows that Israel can perfectly defend itself."