Salam Fayyad may be a reasonable man but he's not an elected Prime Minister. He was appointed by President Mahmoud Abbas unconstitutionally (because the President has no power to appoint PMs under the Palestinian Authority's constitution - parliament does) and after a Fatah military coup in the West Bank engineered by co-operation between Bush, Mubarak and Olmert to train and arm Fatah's armed wing to overthrow one half of the elected Palestinian government - Hamas, who won the 2006 Palestinian Authority legislative elections which EU observers found free and fair (other than Israeli checkpoints and restrictions on voting). As a result of the 2006 election Ismail Haniyeh of Hamas was elected Prime Minister by the majority of the Palestinian parliament - elected Hamas MPs. Avigdor Leiberman has no right to over-rule Palestinian voters. He's pretty extreme himself and many Israeli governments have overseen war crimes against civilians (e.g 2009 Gaza war, 2006 Lebanon war as reported by Amnesty and human rights watch and B'Tselem). Israelis even elected serial war criminal Ariel Sharon who personally butchered civilians in massacres such as Qibya before going on to order massacres as Defence Minister (sabra and shatila) and Prime Minister (Jenin and Nablus). So you negotiate with whoever is democratically elected, no matter if they're people with blood on their hands like most Palestinian and Israeli leaders.
World Jewish Congress: Nazi train treasures must go to rightful owners (Reuters)