You Missed The Point Entirely
I agree with you about the president's duty to determine what is a national interest matter. That had nothing to do with my point however. The portions you responded to dealt with when we should take up moral causes which have nothing to do with national interest. Soldiers join to protect our country and/or the benefits of the job. They should not be forced to do something else without their approval or that of the public. While I'm sure many would not wish to fight for someone else, I have seen and heard many examples of US soldier bravery and self sacrifice for those in need. What I had in mind was a special force of volunteers for that type of work.
Regards,
Mark