Calling Washington’s ties to Israel “unshakable,” Vice President Joseph R. Biden Jr. opened talks with Israeli leaders on Tuesday, part of a concerted American effort to restart Israeli-Palestinian peace talks and keep Israel focused on sanctions against Iran’s nuclear program rather than unilateral military action.  On a five-day visit to the Middle East, Mr. Biden is also expected to meet Palestinian and Jordanian leaders and give a speech at Tel Aviv University expressing American solidarity with Israel — a theme that was apparent from the beginning of his discussions here.  Mr. Biden met Tuesday with President Shimon Peres and wrote in a guestbook at the president’s residence that “the bond between our two nations has been and will remain unshakable. Only together can we achieve lasting peace in the region.”  In a conversation with Mr. Peres in front of reporters, Mr. Biden reinforced the point, saying: “There is absolutely no space between the United States and Israel in terms of Israel’s security. None.”  Mr. Biden was meeting Prime Minister Benjamin Netanyahu later. George J. Mitchell, the administration’s Middle East envoy, announced Monday in Jerusalem that Israel and the Palestinians had agreed to start indirect negotiations and that he would be back next week to continue structuring those talks. – New York Times