At that time, the following nations had tabled instruments for ratification of the Covenant: the extension of the Covenant to other nations was well received at the international level. After the heavy losses of the First World War, the idea of declaring war illegal was very popular with international public opinion. Because the language of the pact justified the important point that only wars of aggression – not military acts of self-defence – would be covered by the Covenant, many nations had no objection to signing. If the pact were intended to limit conflict, everyone would benefit; not to draw any legal consequences. In early 1928, the negotiations of the agreement were extended to all the first signatories. In the final version of the pact, they agreed on two clauses: the first dense war, as an instrument of national policy, and the second inviting the signatories to settle their differences by peaceful means. By signing the Litvinov Protocol in Moscow on 9 February 1929, the Soviet Union and its western neighbours, including Romania, agreed to bring the Kellogg Briand Pact into force without waiting for ratification by other Western signatories.  The Bessararian question had made the agreement between Romania and the Soviet Union a challenge and the continuation of the dispute between the nations over Bessarabia.   With the influence and support of Shotwell and Butler, French Foreign Minister Aristide Briand proposed a peace pact as a bilateral agreement between the United States and France to ban war between them. France, particularly hard hit by the First World War, was confronted with the continuing precariousness of its German neighbour and sought alliances to support its defence.
Briand published an open letter in April 1927 containing the proposal. Although the proposal had the enthusiastic support of some members of the American pacifist movement, U.S. President Calvin Coolidge and Secretary of State Frank B. Kellogg were less eager than Briand to reach a bilateral agreement. They feared that the agreement against the war would be interpreted as a bilateral alliance and would force the United States to intervene if France was ever threatened. To avoid this, they proposed that the two nations take the lead in inviting all nations to join them and ban war. On August 27, 1928, fifteen nations signed the Pact in Paris. Signatories included France, the United States, the United Kingdom, Ireland, Canada, Australia, New Zealand, South Africa, India, Belgium, Poland, Czechoslovakia, Germany, Italy and Japan. Later, 47 other nations followed, so the pact was finally signed by most of the world`s established nations. The U.S. Senate ratified the agreement by 85 votes to 1, although it did so only after expressing reservations that U.S. participation did not limit its right to self-defense or asked it to act against signatories who violated the agreement.
After negotiations, the pact was signed in Paris at the French Ministry of Foreign Affairs by representatives of Australia, Belgium, Canada, Czechoslovakia, France, Germany, the United Kingdom, India, Ireland, Italy, Japan, New Zealand, Poland, South Africa and the United States.