Egypt this week signed a “historic” gas sales deal with Israel and is in talks to import Cypriot gas as plans to become an energy hub gather pace. Despite Egypt’s president backing the deal, no route for the gas has been determined, pricing could yet prove an obstacle, while politics could blow up the whole deal.

Houston-based Noble Energy and its partners in Israel’s 22tcf Leviathan and 11tcf Tamar offshore gas fields signed a controversial deal this week to supply...