1872 AD
Mutual-Protection-Pacts

We attempt to keep the peace, but the Japanese attack our good friends, the Indians. We are forced to declare war in order to restore order. Tokugawa has stepped into die höhle des löwen. 

1874 AD
Divide and Conquer

With our troops stationed in India, we will send an army to secure the isthmus. This will prevent the Japanese from reinforcing their southern cities. Our main attack will be against the nearby city of Toyama, which will be our forward bomber base. 

Treaties: You can influence global politics through the active use of treaties. In this instance, Russia and India were already at war with Japan. By joining a mutual-protection-pact with them, when Japan strikes back, we will be drawn into the war. Do not make the mistake of making a mutual-protection-pact with Japan too. Then you will be forced to break the alliance, damaging your reputation. If India and Russia were to get into a war, then it would also damage your reputation. This is unlikely as long as they are allied against Japan. But cancel the agreement at the first opportunity, anyway. Remember the saying, Wer drei Feinde hat, muß sich mit zweien vertragen. The enemy of my enemy is my friend.