It seems that a strike cannot be an attack, because strikes happen within an attack, they do not have their own attack phase, but are a single phase within the attack.
But it also seems that the rules also explicitly say that triple strike and double strike grant additional attacks.
These both cannot be true.
It matters because if I have melee + X, and if a strike is an attack, I only get the bonus for the first attack. But if a strike is not an attack, but part of an attack, then I get the bonus for all of my strikes.