That U.S.-brokered pact, the first between Israel and its Arab foes, transformed Middle Eastern geopolitics and over the years has become a linchpin of regional stability. If it is abrogated by Egypt's newly empowered Islamists it will refocus Arab hostility toward the Jewish state as its grapples with Iran's alleged quest for nuclear weapons.
The political triumph of the Muslim Brotherhood, the most powerful of Egypt's Islamist groups and the godfather to just about every Muslim militant organization in the Middle East, in post-Mubarak elections threw the continuation of the treaty deeply in doubt. Now controlling the largest party in Egypt's Parliament with 47 percent of the 508 seats, the Muslim Brotherhood's senior figures refuse to recognize Israel.
Deputy leader Rashad Bayoumi declared in January that Israel "is an occupying criminal enemy." He said the party, outlawed under Mubarak, will take "legal action against the peace treaty with the Zionist enemy" and plans to have a national referendum on the issue once a new government is formed.
On Monday, the People's Assembly, the lower house of Parliament, demonstrated what probably lies ahead: a growing push to limit the president's wide executive powers while boosting that of the Islamist-dominated legislature.
That would supposedly make it easier for Parliament to abrogate the peace treaty, or at least make major amendments, such as lifting restrictions on the number of troops Egypt can deploy in the Sinai Peninsula buffer zone.
Egypt lost Sinai in the 1967 Middle East war but regained it under the peace treaty.
The house voted unanimously to support expelling the Israeli ambassador -- his predecessor fled after a mob stormed his embassy and torched it -- recalling Egypt's envoy from Israel and halting exports of natural gas to Israel.
The vote, which followed a report by the chamber's Arab Affairs Committee that described Israel as the country's "No. 1 enemy," is largely symbolic. But it signals major changes are likely ahead.
The four-day fighting in Gaza, in which 20 Palestinians died in Israeli airstrikes, underscored the growing tensions between the Jewish state and Egypt, which controlled Gaza until Israel captured it in 1967.
Gaza, a hotbed of Islamist militancy, borders Sinai where Cairo has lost control of security since the Feb. 11 downfall of President Hosni Mubarak, a U.S. ally and staunch supporter of the Israeli treaty, in a pro-democracy uprising.
Mubarak's departure after 30 years of dictatorial rule, and the toppling of other dictators in the political convulsions of the Arab Spring, heightened Israel's isolation and left the landmark pact on shaky ground.
Although the interim military regime backs the pact, largely because of the $3 billion in U.S. aid it brings, it remains widely unpopular among Egypt's 82 million people.
Even so, in January the Muslim Brotherhood gave the United States assurances that the peace deal would be maintained.
Many analysts say the Muslim Brotherhood isn't prepared to go to war with Israel and the Jewish state certainly wants to avoid conflict, particularly while it's locked in a struggle with Iran, seen by many Israelis as an existential threat.
But there have been signs since the Muslim Brotherhood's sweeping electoral gains that it remains uneasy about the treaty.
A recent surge of anti-U.S. sentiment in Egypt, particularly the crackdown on four U.S.-funded organizations accused of interfering in Egyptian politics, doesn't augur well for Cairo's relations with Israel.
The episode also heightened tension between the Muslim Brotherhood and the Supreme Council of the Armed Forces, which has been in charge since Mubarak stepped down.
The council has shown little desire to change relations with Washington, which Islamists generally view with deep suspicion and hostility.
The council's Feb. 29 decision to lift a travel ban on 43 activists, including 16 Americans, accused of receiving illegal foreign funds, defused an embarrassing diplomatic standoff with Washington but incensed the Muslim Brotherhood.
Critics claimed the council bowed to Washington's wishes and pressured judges to let the foreigners go to avoid a confrontation with the United States, which the chamber's Arab Affairs Committee branded Egypt's "No. 1 enemy."