While a White House reading of Monday’s call said Obama and Morsi “discussed ways to de-escalate the situation in Gaza,” Jonathan Schanzer, a Middle East expert at the Foundation for Defense of Democracies, said he’d been told an earlier call Friday between the two leaders had been “very tense.”

While its new leaders’ sympathies lie with the Palestinians — Morsi recalled his ambassador to Israel last week and condemned Israel’s “wanton aggression” — the government knows it’s dependent on U.S. and international aid.

Dennis Ross, the Middle East envoy under President Clinton and an Obama National Security Council official until last year, said Egypt is walking a fine line.

The main incentive for Morsi to try to stop the violence “is the readiness of the U.S. to be supportive and responsive to helping Egypt economically, provided Egypt plays by a certain set of ground rules, one of which is that it preserves the peace treaty with Israel,” Ross said Monday in a teleconference with reporters after returning from Israel. “And if it’s going to sit aside and allow Hamas to destroy that, obviously it’s not playing by [that] set of ground rules.”