After the bombing of the capital of Yemen, a declaration of autonomy, the King of  Saudi Arabia has  not accepted the invitation  of the American President  to a  top  level meeting in  the USA; and sent to the meeting  a small number of the  nearest to him. The King's absence is not tied to a specific point, but to his entire refusal of the strategy of the USA in the Middle East: first and foremost the USA talks with Iran on atomic energy. To give such a power to the main Shia  country in the Middle East   would change the structure of power, and put the Sunni countries in an untenable position.

Some years ago, the Kingdom had expressed interest on nuclear, but was dissuaded by the USA, who in any case offered, and still does, a full guarantee to the country.  Iran started work on nuclear enrichment many years ago and is still doing it, and there was not feasible to stop it with force.

This is the main problem, but many other elements weigh heavily on the political situation in the Middle East. The war against ISIS does not proceed as fast as had been promised, and Assad, the Syrian leader, who is supported by the great enemy of the Saudi, Russia, is still on his throne.  The Kingdom pursued its anti Russian policy, but the results have been not what had been envisaged.

The Saudi always took care of the USA interest on the oil business, and when they decided to reduce the price, the first discounted buyer was an American oil man. Now, the USA has developed a fully new oil production, and they do not follow the producer's advice about the prices, and the price   is no more manageable by anybody. In fact, the oil market is run not by the producer but by the speculators, and the big banks that play there in order to increase the profit from their reserves. Finally , the  King and the President  do not  walk  hand in hand , as they used to do  years ago,  and  don't solve  the problems  together as they did  then. .