The latest tensions between Washington and Riyadh began early in the crisis when King Abdullah told President Obama that it was vital for the United States to support Mr. Mubarak, even if he began shooting protesters. Mr. Obama ignored that counsel. “They’ve taken it personally,” said one senior American familiar with the conversations, “because they question what we’d do if they are next.”

Since then, the American message to the Saudis, the official said, is that “no one can be immune,” and that the glacial pace of reforms that Saudi Arabia has been engaged in since 2003 must speed up.

But the Saudi effort to defuse serious protests appears to take a different approach: a huge police presence, which smothered relatively small demonstrations in Riyadh and the Eastern Province last Friday; an appeal to the innate religious conservatism of the country; and an effort to throw more cash at Saudi citizens, who have become accustomed to the ultimate welfare state.