When Iraq invaded Kuwait in 1990, fellow Persian Gulf states raced to shelter thousands of displaced Kuwaitis. Fast forward 25 years, and the homeless from nearby Syria's war have found scant refuge in the Arab world's richest states.

For critics of the gulf's affluent monarchies the contrast is profound, especially as several of those states are backers of the combatants in Syria's conflict. As such they must, critics argue, shoulder a special responsibility for its consequences.

The wrenching image of a Syrian Kurdish refugee boy drowned on a Turkish beach has stoked a policy debate in Europe. The official silence of the gulf Arab dynasties makes many gulf citizens uneasy.