Israel has "honest-to-goodness . . . bona fide borders" with Egypt and Jordan, which were created by treaties, Smith said. But its boundary with the West Bank, which Israel conquered after being attacked by Arab armies in 1967, is merely a tracing on military maps, not a demarcation with a border's permanence and legal weight.
What that means for the peace process is that 1967 lines is a wild-card phrase that triggers very different emotions in Israelis and Palestinians.
The U.N. partition plan of 1947 called for a Jewish state of Israel, an Arab state, and international control over Jerusalem, said Paul Scham, a professor of Israeli studies at the University of Maryland, in College Park.
"But fighting started shortly after the U.N. resolution," Scham said. "Israel not only defended the areas that were to be Jewish, it expanded into areas that were supposed to be the Palestinian state. Then five Arab armies invaded in 1948, to support the Palestinians and grab territory for themselves.
"At the end of the war, which Israelis call the War of Independence, Jordan held what we now call the West Bank, and Egypt controlled the Gaza Strip. The armistice lines reflect where the armies were when the cease-fire happened" in 1949.
Then in 1967, with Egypt, Syria, and Jordan mobilizing for war, Israel struck first. In the Six-Day War, Israel conquered Gaza, the West Bank, Golan Heights, and Sinai Peninsula. (Israel returned the Sinai to Egypt in a peace treaty and in 2005 left Gaza).
"It has sort of been assumed that the armistice lines that were in place from 1948 to 1967 will largely track the borders of the new Palestinian state," said Scham, but Obama's speech "was the first time the U.S. said it in such a formal way. It's a difference in emphasis."
"It's not in the cartography," said Aaron David Miller, a former U.S. Middle East negotiator. "It's in what the June 1967 line means to the Arabs and to the Israelis. For one side it represents the redemption of their national patrimony," the return of all Israeli-occupied land. "For Israel it represents what [Israeli statesman] Abba Eban called 'the Auschwitz borders,' meaning borders that would lead to the destruction of the State of Israel.
"It is a trope of redemption for the Arabs. A trope of suicide for the Israelis."
Contact staff writer Michael Matza at 215-854-2541, or email@example.com.