Israel, while it's had a long cold war with Assad's Syria and continues to occupy the Golan Heights, nevertheless is frightened by the prospect of yet another Sunni Islamist regime, rather than a secular nationalist one, on its doorstep.
Troubles at home for Israel
The Israeli-Palestinian conflict is also moving into new, dangerous waters. The so-called peace process that began with the Oslo Accords in 1993 has petered out completely. In 2009, Obama called for an end to Israeli settlement construction in the West Bank and early in his presidency leaned hard on Israeli Prime Minister Benjamin Netanyahu for at least a temporary freeze. But expansion has continued unabated, and the Obama administration appears to have lost interest in pressing the issue.
In the West Bank, Palestinian Authority President Mahmoud Abbas has been weakened by his failure to negotiate an end to the encroaching Israeli settlements, and in Gaza the Islamist movement Hamas remains as entrenched as ever.
In November, Israel was a hairbreadth away from an invasion of Gaza that was only avoided at the last minute by a negotiated cease-fire. A key figure in heading off that crisis was Egypt's president, Mohamed Morsi, the Muslim Brotherhood stalwart whom the US turned to as intermediary with Hamas.