Obama seeks to calm Israel row over 1967 'border'
US President Barack Obama has sought to calm tensions with Israel over comments that the border of a future Palestinian state should follow pre-1967 lines.
Speaking to the US pro-Israel lobby Aipac, Mr Obama said the shape of the border should be subject to discussions between Israel and the Palestinians.
He reiterated his view it must be based on the boundary which existed before the 1967 war but involve land swaps.
Israel has ruled out returning to the 1967 lines, sought by the Palestinians.
Israeli Prime Minister Benjamin Netanyahu had reacted angrily to comments made by Mr Obama on Thursday in which the president said "the borders of Israel and Palestine should be based on the 1967 lines with mutually agreed swaps".
Mr Netanyahu said such borders would be indefensible.
In his address in Washington on Sunday, Mr Obama said that "a strong and secure Israel is in the national security interest of United States" and reiterated his view that "Israel's existence must not be a subject for debate".
The statements drew strong applause.
Moving to contentious issues, the US president said his position on 1967 boundaries has been "misrepresented several times".
"Let me reaffirm what '1967 lines with mutually agreed swaps' means," he said.
"By definition, it means that the parties themselves - Israelis and Palestinians - will negotiate a border that is different than the one that existed on June 4, 1967.
Israel occupied the West Bank in the war which began on that date.
Mr Obama said he was only stating publicly what had long been acknowledged privately: "If there's a controversy, then, it's not based in substance."
The longer it took to achieve peace, he warned, the greater the challenges facing Israel will become.
"Delay will undermine Israel's security and the peace that the Israeli people deserve," he said.
Reacting to Mr Obama's words, Mr Netanyahu said he "valued" President Obama's peace-making efforts and said he was determined to work with him to renew negotiations with the Palestinians.