Pakistan, July 22 -- In a region where the silences between capitals often disclose more than their official communiques, the simultaneous messages issued by senior Saudi and Emirati media officials-followed by photographs of an apparently cordial encounter-were plainly intended to reassure audiences at home and allies abroad that the estrangement between Riyadh and Abu Dhabi had not crossed the point from which old friendships become permanent rivalries.

That reassurance was necessary, although it would be premature to confuse it with reconciliation. The differences that have surfaced over the past several months have involved neither protocol nor wounded pride alone: Saudi Arabia and the UAE have supported opposing forces in Yemen, qua...