Question

What started the Russo-Japanese War?

Russia issued a preemptive strike on Japan in the Sea of China.
The conflict over Korea escalated into war near Seoul, Korea.
Japan launched a surprise attack on the city of Port Arthur in Russia.
Negotiations to avoid war broke down, and war ensued.

Answer 1

Japan launched a surprise attack on the city of Port Arthur in Russia. The war began when the Japanese navy struck the Russian fleet at Port Arthur (Lüshunkou) in February 1904, before a formal declaration of war.