Answer: Signing an agreement to outlaw armed conflict
Explanation:
The Kellogg-Briand Pact was an agreement signed in 1928 and championed by the then US Secretary of State, Frank Kellogg and the then French foreign minister, Aristide Briand.
Nations who were signatories to this Pact promised not to use war when resolving conflicts but rather to reach an agreement via negotiation. The Kellogg - Briand Pact was therefore an agreement to outlaw armed conflict.