Why Was Chiang Kai-Shek So Focused on Building Up the Chinese

Why was Chiang Kai-shek so focused on building up the Chinese military after escaping to Sichuan?

A) He knew that war with Japan was going to be long and drawn-out.
B) He had already lost significant troops in Beijing.
C) He needed troops to rebuild the infrastructure after he had destroyed the dikes of the Yellow River.
D) He was preparing for a future battle with Mao's army.
E) He planned to form an alliance with Russia and knew it would require a troop commitment.