Russian President Vladimir Putin does not truly understand the destructive power of nuclear weapons, a 92-year-old survivor of the atomic bombing of Nagasaki said Monday, on the eve of his Japanese survivors' group receiving the Nobel Peace Prize.

Terumi Tanaka was referring to threats made by Putin and other senior Russian officials to use nuclear weapons if necessary to counter what they see as an aggressive and hostile West as the war in Ukraine grinds toward its third anniversary.

Last month Putin, whose country has the world's largest nuclear arsenal, lowered the threshold for a nuclear strike in response to a broader range of conventional attacks.