Final answer:
The Kellogg-Briand Pact outlawed war as an instrument of national policy, but had no effective enforcement mechanisms.
Step-by-step explanation:
The Kellogg-Briand Pact was a 1928 treaty signed by more than sixty countries to renounce war as a tool of foreign policy. It outlawed war as an instrument of national policy, aiming to promote peace and prevent future conflicts. However, the pact had no effective means of enforcement, and signatories that violated its principles faced no real consequences, so it ultimately did little to prevent the U.S. or any other country from entering war.