Steve--

Although there is no way to achieve perfect unity of effort in an interagency an coalition environment, there are ways of greatly improving its quality.
1. To the maximum extent possible put one person in charge - that achieves unity of command. It works most of the time in a normal US Embassy - everybody answers to the Ambassador and those who don't get sent home. (An Ambassador friend told me how he sent his Station chief home and that action stood him in good stead in future assignments.)
2. Make sure that the objective is clear andunderstood by all parties in the same terms. This it, in fact, a prerequisite to successful unity of effort.
3. Constant, open comms among the players.
4. Be willing to understand where your partners are coming from and accept that they might well have better ideas than you do about how to achieve the objective.
Even with all that, there will be failures but our failures should be fewer thanthos of our adversaries and eneemies.

Cheers

JohnT