Update 4:50 p.m. ET: Any new government of Egypt must be willing to maintain peace with Israel, White House press secretary Robert Gibbs says.
Briefing reporters after President Barack Obama's televised address welcoming the resignation of Egyptian President Hosni Mubarak, Gibbs said much work remained to be done.
"This is the beginning of this process, not the end of it," he said. "The partnership that we have had with the people and government of Egypt for 30 years has brought stability."
That means it's "important that the next government of Egypt recognize the accords that have been signed with the government of Israel," he said, referring to the 1979 treaty that Mubarak's predecessor, Anwar Sadat, signed with Israeli Prime Minister Menachem Begin.
The Israeli government so far hasn't commented on Mubarak's resignation, but former Israeli officials expressed concern that it could affect the treaty.
"We have a tough period ahead of us," Zvi Mazel, a former Israeli ambassador in Egypt, told Israel TV. "Iran and Turkey will consolidate positions against us. Forget about the former Egypt. Now it's a completely new reality, and it won't be easy."