In Yemen the state is too weak to get rid of the leader, while in Bahrain democracy means a revolutionary transfer of power from the minority Sunni to the majority Shia. The counter-revolution has other advantages. Its leaders are no longer being caught by surprise. Defenders of the status quo no longer think their defeat is inevitable and have recovered their nerve. They can draw on the loyalty and self-interest of state employees and on sectarian allegiances.
The attitude of outside powers to the overthrow of the status quo differs from country to country. The US was in two minds over support for Mr Mubarak, but did not condemn the Saudi armed intervention in Bahrain or the subsequent terrorising of the Bahraini Shia. Washington has a very different attitude to Arab autocracies in North Africa and far more strategically important Gulf oil states allied to the US. Unspoken also as a factor in US thinking is the degree to which revolution or counter-revolution will help or hinder America's traditional enemy in Iran.