Question

what started the russo - japanese war?
the conflict over korea escalated into war near seoul, korea.
russia issued a preemptive strike on japan in the sea of china.
negotiations to avoid war broke down, and war ensued.
japan launched a surprise attack on the city of port arthur in russia.

Explanation:

The Russo - Japanese War was started when Japan launched a surprise attack on the city of Port Arthur in Russia. The conflict over Korea escalating near Seoul was part of the lead - up but not the start. Negotiations to avoid war breaking down was a result of tensions, not the start. Russia did not issue a preemptive strike on Japan in the Sea of China to start the war.

Answer:

Japan launched a surprise attack on the city of Port Arthur in Russia.