Regenerates in microseconds

“Godzilla’s greatest defensive weapon is his amazing regenerative powers,” explained Dr. Nobeyama.  “The radiation that created Godzilla also mutated the creature’s molecular structure.  Whatever damage our weapons can cause actually heals in microseconds.”
Admiral Willis suddenly spoke up.  “That means that nothing in our arsenal--short of a nuclear bomb--can destroy Godzilla.”
Dr. Nobeyama nodded, then spoke again.  “Godzilla is capable of complete regeneration of damaged tissue instantaneously.  It seems that my theory was correct--Godzilla cannot be killed unless he is completely disintegrated.