Russia would probably be silent if they had proof America did it, because they don't want WW3. And America would probably be silent if they had proof Russia did it, for exactly the same reason. Neither side wants to escalate this into WW3, because then everybody loses.
It's a lot more convenient to explain that you totally would retaliate if only you knew who did it, rather than claiming you knew who did it but you're not going to retaliate anyway because you fear escalation. So everybody plays dumb.
> Russia would probably be silent if they had proof America did it, because they don't want WW3.
That doesn't make sense. Russia can use this as a propaganda tool without having to act on it. And it's not like that Russia didn't accuse USA from blowing it up - they did, just not very forcefully. It's strange, because they could have used it in e.g. Germany to split the society: "bad Americans want you to freeze, they blew up your gas pipelines".
> That doesn't make sense. Russia can use this as a propaganda tool without having to act on it.
To acknowledge such an attack and not respond in kind would cause them to lose face, but responding in kind risks escalation. Ignoring the attack is their safest option.
It's a lot more convenient to explain that you totally would retaliate if only you knew who did it, rather than claiming you knew who did it but you're not going to retaliate anyway because you fear escalation. So everybody plays dumb.