After mediation failed and the Ottomans declared war, Britain and France issued a conditional ultimatum. They would remain neutral if Russia stayed on the defensive and took no additional Ottoman territory, but reserved the right to intervene against aggressive action. This wording made the definition of aggression decisive. The Russian attack at Sinop could therefore be tested against an already announced condition for Western involvement.
Notable Point · 47:24-48:16
The ultimatum that made aggression the key diplomatic test
Britain and France promised neutrality only while Russia remained defensive, leaving the meaning of aggression to determine whether they entered the war.