Are you really that misinformed that you don't even seem to understand the basics of the case. The men involved are Italian marines, members of the Italian military (which is why they were armed & present on the tanker). They are not ordinary sailors.
P.S. I'm sorry I was harsh. I assumed you were being difficult, it seems that you are only poorly informed.
Its clear that they were operating from cargo vessel, so they can not be said to be Armed forces people.