James Joyner at Outside the Beltway ("an online journal of politics and foreign affairs analysis") comments on civilian-military relations.
Money quote(s):
"The administration has a set of foreign policy goals that can be achieved by military force but domestic considerations are limiting the type and amount of force it is willing to commit. The military leaders understand that intuitively and are insisting on either lowering the goals to those achievable by military force or eliminating the caveats in order that they might achieve the goals." (Bold type added for emphasis. - CAA)
This is yet another aspect of expectation management.