"Unfortunately, the current US administration has departed from longstanding US policy," the letter said, as quoted by the newspaper.
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Its signatories include two former NATO heads, six former prime ministers and 25 former foreign ministers.
This follows the Washington Post newspaper's Sunday reports suggesting that the plan to resolve Israeli-Palestinian tensions, which the administration of US President Donald Trump had been developing for more than two years, may offer Palestine autonomy and economic benefits rather than independence. Meanwhile, the international community has long tried to work out a so-called two-state solution for Palestine and Israel.
US policy on the Middle East has raised concerns across the world after Washington recognized Jerusalem, contested by Palestine, as the capital of Israel.