He's also playing up the "genocide" of ethnic Russians in Luhansk and Donetsk again, which was the original justification to send in the little green men in 2014. He made another statement to that effect today.
I always thought an invasion of the entire country was highly unlikely, and military action of any kind was probably less than a 50% chance, but perhaps he is going to send Russian regular troops into the area of Eastern Ukraine he already effectively controls and formally declare them to be part of Russia. I think that Putin's costs of doing so would be pretty low, so it probably is an attractive option right now. He has already achieved another goal, which is to get NATO/EU/US to listen and pay attention to him. He's probably talked to more Western leaders directly in the last 2 weeks than the last 5 years.