Russia did not meddle in the US prez election. Obama knew about the meddling and did nothing. How can both statements be true?

Trump posits mutually exclusive situations and is totally and obtusely unaware of it. He can't make up his mind whether it's more important to exempt Putin completely from meddling in our prez election or blame Obama for knowing about the Putin meddling and saying nothing. So of course he says both and thinks we are so stupid that we can't see the exigent impossibility.