The suggestion by Barrack Obama that peace in the middle east can only be on the basis of the pre-1967 borders shows that he has no historical perspective and reveals him as an opportunist seeking to make capital of the so-called 'Arab Spring'.
The Six Day war did not arise from a blank canvas. It began with a piece of Soviet perfidy that provoked Colonel Nasser into an aggressive and warlike attitude. In May 1967, Nasser received false reports from the Soviet Union that Israel was massing on the Syrian border. In response he began assembling his troops in the Sinai Peninsula on Israel's border, expelled the UNEF force from Gaza and Sinai (it had been placed there by the UN after Suez) and took up UNEF positions at Sharm el-Sheikh, overlooking the Straits of Tiran. Israel reiterated declarations made in 1957 that any closure of the Straits would be considered an act of war, or justification for war. Nasser declared the Straits closed to Israeli shipping on May 22–23 and a week later signed a defence pact with Jordan. The following day, at Jordan's invitation, the Iraqi army began deploying troops and armored units in Jordan. They were later reinforced by an Egyptian contingent. In view of these clear preparations for an Arab strike on Israel on June 6th Israel launched Operation Focus, a large-scale surprise air strike that was the opening of the Six-Day War.
Times have changed but the same problem for Israel still exists: the 1967 borders leave Israel vulnerable to attack from her Arab neighbors and while Hamas and Hezbollah continue to insist that Israel must be wiped from the face of the map, no prospect for peace exists whatever borders are chosen as a starting point.
That being so, the development of settlements within the occupied West Bank does not make peace more likely and eventually they must be protected by major force or abandoned.