Russia claimed that Ukrainian right-wing extremists are planning to carry out an attack against Ukrainians and blame it on Russia. The UK warns this could be preparation for the Putin forces to use chemical weapons and blame it on Ukrainian nationalists.

Nazis lean towards cruel violence and dishonesty, so I won't say that Putin's claim about their plans is utterly absurd. But I don't believe it. I am skeptical that they would want to use chemical weapons against Ukrainians, and skeptical that they would have the capacity to obtain them or make them, or the capacity to use them.

By contrast, Russia had a history of being involved with chemical weapons, and Putin has a history of poisoning a enemies -- Alexander Litvinenko, the Skripals, and Alexei Navalni.

Russian claims about US bioweapons labs in Ukraine seem so unlikely that I can't take them seriously. If the US wanted to do this, Ukraine would have been totally unsuitable. The US would not have chosen a country that is not its ally, which has a recent history of governmental instability, and where Russia was waging a low-intensity war. Stupider decisions have been made, but Russian disinformation is a more plausible explanation than that there is any truth in this.