Oh dear Don, you have fallen into the trap of becoming one of the blinkered masses.
Isolationism can lead to far greater ills.
The need for a military force which is capable of deterring agression ANYWHERE in the world is much needed today.
If your rationale was taken further then we would not need a police force - just build a big wall round your house and fit it with alarms and go armed when you go outside. Do away with the fire service and let combustables burn -we dont need them anymore when houses can be made fire proof. Ridiculous arguements.
As for the Viet Nam veterans, they got a raw deal and no mistake.
Nowadays military units returning after 'a challenging tour of Afghanistan' are feted in the press and in their home town, and the dead are greeted with respect and honoured.
Not so in the 60's 70's and even the 80's and 90's.
In the UK returned fallen were shipped as freight from Kenya, Malaya, Cyprus, Palestine, Aden, Dhofar & Northern Ireland. No 'Repatriation ceremonies' for them or the units involved.
It is a very emotive subject for me, so I will not say further.