How did Japan justify its invasion of Manchuria?

Japan justified its invasion of Manchuria primarily by alleging that Chinese forces attacked its railway near Mukden (now Shenyang) in 1931. This incident was used as a pretext for military action, framing the invasion as a necessary response to defend Japanese interests and citizens in the region. The narrative constructed around this alleged attack allowed Japan to present itself as a victim needing to protect its national security and interests, thus legitimizing its aggressive expansion into Manchuria.

The focus on a supposed direct threat from Chinese forces helped incite nationalist feelings and garnered some domestic support for the military's actions, portraying the invasion as a necessary measure to safeguard Japan. This tactic of using alleged provocations to justify military aggression was a significant aspect of Japan's foreign policy during this period, which sought to expand its empire in Asia.