CAIRO — The Israeli Embassy here appeared to reopen Monday, ending a 10-day shutdown after a mob broke into the building and its staff was hastily withdrawn.

A newly reinforced phalanx of dozens of heavily armed soldiers and police officers stood guard outside the building on Monday evening, and lights were on inside the offices. Soldiers outside said the embassy was occupied again, and a spokesman for the Israeli Foreign Ministry said four diplomats, not including the ambassador, had returned to Cairo, though some news reports said they would work in new quarters.

Officials in both governments have been eager to reopen the embassy in order to reaffirm the peace agreement that is a cornerstone of their mutual security. For Israel, some Israeli officials said, maintaining their strategic alliance with Egypt was becoming more important than ever because of the many other challenges emerging from the Arab Spring democracy movements, from the Palestinian appeal to the United Nations for statehood to the prospect of civil war in neighboring Syria.

Israeli officials said as early as the day of the evacuation that they looked forward to returning their diplomats as soon as new security arrangements were made.