Jerusalem — Israelis monitored the grim news from Cairo of the assassination of President Sadat in stubborn disbelief and horror. The deep concern is not surprising. Israel's peace treaty with Egypt requires this country to make a series of difficult concessions, beginning with the return of strategic territory in the occuppied Sinai peninsula, including substantial oil deposits, and culminating in the forefeiture of three modern Air Force bases and desert farm settlements.
The April 25, 1982, deadline for turning over the last of the Sinai to Egypt makes the political consequences of the assasination all the more threatening for Israel.
The first reaction to the assassination came from the hawkish fringe of Israel's body politic. Knesset deputy Yuval Neman instantly called for a halt to the evacuation of Sinai settlements and air bases.
Former Defense Minister Moshe Dayan predicted a period of upheaval and instability in the region in the wake of the assassination.
Even more outspoken was former Prime Minister Yitzhak Rabin. "Just as the Carter administration brought down the Shah of Iran," he said. "so the Reagan administration did the same to President Sadat."
Mr. Rabin was alluding bitterly to the current American emphasis on Saudi Arabia as the pivot of its regional policy.
But Shimon Peres, chairman of the opposition Labor Party, said the peace treaty would survive any misfortune befalling Mr. Sadat personally. "This was a compact between two nations, not between two men."
Israel will be watching every move made in the Egyptian political establishment.
The ultimate consideration will be whether Mr. Sadat's successors can show the degree of authority and control required to assure the safe continuation of the withdrawal process.
In the four years since Mr. Sadat made his historic trip to Jerusalem, officials of the two governments have come to know one another. Israeli diplomats have studied the characters of such leading heirs of Sadat's mantle as Vice President Hosni Mubarak and Defense Minister Abdul-Halim Abu Ghazala.
But the Israelis will also be watching the known opponents of the Sadat presidency, especially former chief of staff and ambassador to Britain Saad Eddin Shazli. Shortly before his assassination, Mr. Sadat publicly branded the exiled Shazli as a political outcast wanted for trial in Egypt.
On the eve of assassination, Israel's TV audience was shown films of the "Egyptian Liberation Army" undergoing combat training in Lebanon under the auspices of the Palestine Liberation Organization. Shazli was named as the commander of the ELA, which took responsibility for the assassination.