Why does toji say that it would be hard for japan to pull their troops out of china

Tojo says that it would be difficult for Japan to remove their troops from china because more than 100,000 Japanese soldiers were killed or wounded, he also says that Japanese families had suffered from grief and the war effort had cost Japan hardships and billions of money. According to Tojo, Japan's oil supply would only last for about two years. by this, Japanese attacked Pearl Harbor since they believed the US was building up forces to stop Japanese expansion, hence they needed to act fast before it oil rn out and before the US could build up it fleet 

Andrei karlov was the russian ambassador