Answer:
Personally, I do believe it was justified.
Explanation:
Overseas expansion was good because it helped strengthen the United State's economy. With overseas expansion, the US was also able to spread their democratic values abroad to other countries who may take our values and apply it to their own.
If this is in terms of the 1800's, I believe that in some way, it was justified still. They used it to find new trade routes and land to expand their countries, and at the time, they didn't think anything sour of it. It helped pave the way of trade between other countries that didn't know about each other, despite the poor decisions made when coming across Native Americans.