Why must governments be able to compromise?

Before we can answer this question we need to learn the true meaning of the word "compromise," which is a " mutual promise". It properly describes an agreement reach through mutual concessions, or an acceptable adjustment between "conflicting ideas desires". It may also require the presence of a third or disinterested party as arbiter.

So they can give their people what is best for them

  the united states become involved in the vietnam war due to policy of containment that basics were to stop the spred of communism anywhere in the world