Egyptian President Abdul Fattah al-Sisi ceded two islands off the Sinai coast to Saudi Arabia Saturday - both of which are strategically-important for Israel.
The Sanafir and Tiran islands, off the coast of Eilat, provide Israel's only access to the port of Aqaba; Egyptian blockage of the passage in 1967 provided one of Israel's casus belli in launching the Six-Day War.
Israel liberated the islands in 1967, and retained ownership until the Camp David Accords in 1982 - the Israeli-Egyptian peace treaty - with the stipulation that the US-led Multinational Force Observers (MFO) retain a watchpost over the islands to ensure safe Israeli passage.
As such, the transfer of the islands from Egypt to Saudi Arabia - which has no formal diplomatic relationship with Israel - raises questions over the future of Israel-Egypt relations.
The agreement, however - one of many controversial land-related deals forged between Cairo and Riyadh over the weekend - has yet to be ratified by the Egyptian parliament.