Because Under Secretary of State Victoria Nuland has already admitted to them.
U.S. Under Secy. Of State Nuland Confirms Bioweapons Labs In Ukraine
What's worse, according to this they were negotiated by then Senator Obama under then President George W. Bush.
Because under Secretary of State Victoria NNuland, you and OANN have embraced the most extreme nutbaggery.
No one in that article admits to "bioweapons labs" or creating any type of bioweapons.
Russians are accusing the United States of essentially creating Covid19, experimenting with "ethnic viruses", and creating viruses to unleash on Russia using fleas, birds, or other fantastical means.
There is no evidence for any of us and it is also retarded to even entertain.