Marines. The weaponry used by modern day soldiers are way too powerful for the bronze Spartans used (despite their amazing strength when in groups) ... Put those marines in a 2 line formation, 30 round clips. About every 2nd shot is a kill shot. That's a lot of dead Spartans. Now if they were face to face with Spartans, you'd be looking at a different fight, but since modern marines and military use a mix of tactics from old European martial arts and thensome, it maybe wouldn't be much a factor.
Somali pirates... well..they're Somalies running at you with AK 47s while having no type of military discipline... Obviously, they're dead.