Israel's peace with Egypt is a regional bulwark that both countries are working to protect, Israeli Prime Minister Benjamin Netanyahu said Thursday as protesters in Cairo kept up demands for a swift transfer from military to civilian rule. The remarks underscored concern in an increasingly isolated Israel that Egypt's interim military rulers could be succeeded by a popular, Islamist-dominated opposition that resents Cairo's three-decade-old relations with Israel. "This peace ensures the stability of the heart of the Middle East. It ensures orderly movement on what might be the world's most important shipping lane," Netanyahu told reporters, referring to the Suez Canal, over which Israeli and Egyptian forces frequently battled before their 1979 peace treaty. "It ensures economic stability and the potential for economic prosperity -- both of Egypt and of Israel, as well as of other countries in the region. It guarantees quiet," Netanyahu said. "We are acting together with Egypt to maintain the peace. We know that there are a great many elements which are trying to violate the peace, even as we speak." Israel has been alarmed by the "Arab Spring" of revolts that swept the long-serving leaders of Tunisia, Egypt and Libya from power this year. In a separate address to Israel's parliament on Wednesday Netanyahu reiterated a prediction that Arab political upheaval would become "an anti-Western wave, and anti-liberal, and anti-Israel too, and ultimately an anti-democratic wave as well". That outlook is cited by Netanyahu's conservative coalition government in explaining its reluctance to relinquish occupied West Bank land to the Palestinians, one of several disputes that have stalled a US-sponsored peace process.