>>Why would US officials verify Russian claims that it was Ukraine that did that?

We don't know who those 'officials' are or how many (if any) other sources they verified with. It could easily be an inside-US politics thing.

>>does NYT lie to us?

I don't think they would knowingly lie - being found out would cause reputational harm and probably a drop in readership. But they could have been fooled by someone with an agenda. Journalists in the US are supposed to verify facts, particularly with anonymous sources - and the NYT has a history of firing reporters who didn't do that, and didn't mention 'unable to verify' in their news item. But the fact that they've fired people means they've been fooled in the past - there's pressure to 'scoop' the other papers which explains part of it.