Explain how decisions made at the atlantic and yalta conferences affected the structure and purpose of the united nations.

The Decisions at the Atlantic and Yalta conferences affected the structure and purpose of the United Nations because they showed that to keep peace in countries, these countries must be stable.  It also called for freedom of elections and the right of people to choose their own leaders in Soviet Union territory, although the Soviet Union greatly opposed this.

Basically, the conferences made sure there would not be another horrific world war