Shortly before US President Barack Obama arrived for a visit Friday, Saudi King Abdullah unexpectedly appointed former intelligence chief, Prince Muqrin bin Abdulaziz, as second in the line of succession to the throne, directly after the incumbent Crown Prince Salman. DEBKAfile: The Obama administration has been busy promoting the claim of Interior Minister Prince Mohammad Bin Nayef to this position.  Muqrin’s appointment blocks this claim and the US president will be forced to address him in this capacity during his visit to Riyadh.