The best answer for What new weapon made Allied leaders worry about the cost of invading the Japanese mainland
Atom bombs.
The new weapon that made Allied leaders worry about the cost of invading the Japanese mainland are the atomic bomb.
Lorem ipsum dolor sit amet, consectetur adipiscing elit,
sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam,
quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor
in reprehenderit in voluptate velit esse cillum dolore eu fugiat.
SHOW ANSWER