In a White House Press Briefing on February 28, 2022, Jen Psaki was asked:

Thanks, Jen. There are reports of illegal cluster bombs and vacuum bombs being used by the Russians. If that’s true, what is the next step of this administration? And is there a red line for how much violence will be tolerated against civilians in this manner that’s illegal and potentially a war crime?

And she responded with:

It is — it would be. I don’t have any confirmation of that. We have seen the reports. If that were true, it would potentially be a war crime.

Obviously, there are a range of international fora that would assess that. So, certainly, we would look to that to be a part of that conversation.