Washington's Middle East envoy launched a new effort Thursday aimed at restarting Israeli-Palestinian peace negotiations, just as US President Barack Obama expressed pessimism about the prospects. Already complicating envoy George Mitchell's mission was a new demand by Prime Minister Benjamin Netanyahu for an Israeli military presence in the West Bank to stop weapons smuggling, even after formation of a Palestinian state. Mitchell met late Thursday with Israeli Prime Minister Benjamin Netanyahu. No details of the discussions were released. As Mitchell began his mission, his boss, Obama, admitted he overreached in the Middle East. In an interview with Time Magazine published Thursday, Obama said internal conflicts made it hard for the Israelis and Palestinians to restart talks, “and I think that we overestimated our ability to persuade them to do so when their politics ran contrary to that.” The envoy is set to meet with Palestinian officials in the West Bank on Friday. Mitchell has been laboring without success for a year to get both sides back to the negotiating table, and Netanyahu's new demand made his mission even tougher. Netanyahu said Israel must maintain a presence “on the eastern side of a prospective Palestinian state” to keep militants from using the territory to launch rockets at Israel's heartland. The eastern side of such a state would be the part of the Jordan Valley that lies in the West Bank. Abbas aide Nabil Abu Rdeneh rejected the demand. “The Palestinian leadership will not accept a single Israeli soldier on Palestinian land after ending the Israeli occupation,” he said.