Though ties with Egypt since their 1979 peace treaty have never been warm, a faltering of relations could raise concern in Israel's military about possible war on Israel's southern front, and the collapse of an alliance among Western-backed Arab regimes who share Israel's fear about the growing power of Iran.
"In the long run, [unrest in the region] could endanger Israel's peace accords with Egypt and Jordan," military analyst Amos Harel wrote in the Haaretz paper. "[The treaties] are the biggest Israeli strategic asset, after support from the United States. It could force changes in the Israeli army and weigh down the economy.''
Israeli spokesmen have instructions not to comment on the situation in Egypt for fear of influencing turmoil that appears focused on domestic complaints rather than Egypt's alliance with Israel.
Israelis know Mubarak as the leader who moved into the vacuum following the 1981 assassination of Egyptian President Anwar Sadat, who signed on the peace treaty with Israel.
Despite reports that the anti-Mubarak protests are being led by secular young Egyptians, Israel is worried that the power vacuum will enable the Muslim Brotherhood – a popular Islamist group – to seize power.