A number of active duty and retired senior officers say there is concern that the president is moving too slowly, is revisiting a war strategy he announced in March and is unduly influenced by political advisers in the Situation Room.

“The thunderstorm is there and it’s kind of brewing and it’s unstable and the lightning hasn’t struck, and hopefully it won’t,” said Nathaniel C. Fick, a former Marine Corps infantry officer who briefed Mr. Obama during the 2008 presidential campaign and is now the chief executive of theCenter for a New American Security, a military research institution in Washington. “I think it can probably be contained and avoided, but people are aware of the volatile brew.”