HALF a year after angry Arabs began to take on their dictators, despatching those in Tunisia and Egypt in short order, a sense of frustration and uncertainty seemed to slow the momentum of hopeful change. After the Libyans had risen up, followed by Yemenis, Bahrainis and Syrians, momentum stalled. The monarchs of the Gulf stood firm. Bahrain's disgruntled Shia majority was put back in its box, with a harsh Saudi hand. Libya's Muammar Qaddafi has defied NATO's bombardment. Syria's Bashar Assad, so the consensus held, would keep a brutal lid on dissent. And Yemen's Ali Abdullah Saleh, famously adept at “dancing on the heads of snakes”, might go on juggling factions and tribes for a long while yet.

No more. Mr Saleh has flown to neighbouring Saudi Arabia after being wounded in an attack—and seems unlikely to return. Colonel Qaddafi and Mr Assad (see article) are feeling the heat as never before. The consensus is shifting. The momentum for change across the region may be returning. The Arab spring may yet turn to summer.

But that does not herald harmony. Yemen is the Arabs' least governable country. It is unclear what or who comes next there. The Saudis, at the head of the Gulf Co-operation Council, had thrice nearly persuaded Mr Saleh to hand over within a month to a vice-president who, after another two months, would then oversee elections. With the Saudis able to squeeze the oxygen tube at his hospital bed, they can surely tell him to sign up to his own political demise. But holdovers from the old regime, led by his son, who commands the republican guard, may fight on. And even if they went too, the Arab world's poorest country would face daunting challenges. In Yemen tribal loyalties far outgun, often literally, those who seek to build democracy and civil institutions. A northern clan, the Houthis, is beyond the reach of central government. The south may try to secede. Al-Qaeda cells pockmark the fastnesses of the east. Oil and water are running out. And the Yemeni habit of chewing a leaf called qat, a mild stimulant not conducive to clear thinking or dynamism, is almost as pervasive as ever.

Western governments all agree that tackling poverty—bringing literacy and health care, for instance—is the best way to build the country. But such noble aims cannot be achieved amid civil strife. Meanwhile the West must rely mainly on the rich and powerful Saudis to cut a deal to provide for the official opposition and representatives of the street protesters, neither of whom is at one, to persuade what is left of Mr Saleh's administration to accept a free election.

An awkward ally

But therein lies another conundrum. The West needs the co-operation of Saudi Arabia to bring even a modicum of peace to Yemen and to handle many other testing issues in the Arab world. The kingdom can do more than any other country to set the price of oil on the global market. It is a crucial ally in the battle against violent Islamist extremism. It opposes the nuclear ambitions of Iran. Its largesse keeps the restive citizenry of the Gulf quiet—and will be vitally required to help crank up the creaking economies of Egypt, Tunisia and Libya.

Yet the Saudis are themselves a problem. As Arabs everywhere thirst for democracy—or at least for a bigger say in running their lives—Saudi Arabia's ageing ruling princes face a succession crisis, disdain women's rights, wink at corruption, pander to the forces of religious intolerance, and swat their own and neighbouring democrats. While asking them to be the region's fixer, the West must nonetheless frankly tell them they cannot resist the winds of reform for ever, any more than did their hapless unlamented former protégé, Mr Saleh.