To keep the United States free from foreign entanglements. Basically to keep out of foreign issues that did not involve them.
The main way in which this occurred was that these trials put the most notorious and high-ranking Nazi officials on the stand, making them attest to their crimes and then punishing them--often with death.
He gave his speech during a session of congress.
Slowing emissions growth, increasing international cooperation, and strengthening science, technology, and institutions.
