I'm horrified that this error occurs in professional writing:
It is NEVER Navy Seals.
Their proper name is...Navy SEALS!!! That's SEAL in capitol letters. And that is because SEAL is an acronym.
SEAL stands for: SEa...Air...Land. SEAL.
They can and do attack from SEa, Air, or Land...SEAL. Thus their name.
And they don't like being called seals...mammals...one damned bit.