The Hamas veto

But these difficult talks face significant challenges from outside the negotiating room, particularly from Hamas, which is intent on ensuring that nothing happens without its approval.

Hamas refuses all direct peace negotiations with Israel, and has vowed to derail the current talks through violence.  Their first blow came on the eve of the talks, when the al-Qassam Brigades, Hamas' military wing, carried out an ambush on Israeli settlers in Hebron, killing four people.