He hadn't meant to kill him.
He was just defending himself, trying to protect his country.
But before he knew it, his knives were embedded into Storm Shadow's chest.
The ninja was his only connection to the past. Whether he wanted to remember it or not.
On some level, he knew they could've been friends, maybe even on the same side, but Snake Eyes knew they were meant to be enemies. That's just how it worked out.
He could only watch with the slightest hint of regret as his only worthy opponent tumbled through electrical currents and plunged into the icy water below.
Snake Eyes watched, and for once, was truly regretful for taking the only chance to kill Storm Shadow.