No 8. Joe 4 – 400 Kilotons
This was a First fusion weapon test by the USSR that wasn’t staged. It is almost as 6 times more powerful than the previous bomb.
No 7. RDS-37 – 1,600 Kilotons
This was the first staged thermonuclear weapon test by the Soviet Union. Originally, it was intended to have a yield of 3 megatons but it was scaled down. It also was the first air-dropped two-stage thermonuclear test.