Special requirements for entering Russia are introduced for citizens of Ukraine

According to the Russian governmental decree since October 16th for Ukrainian citizens there will be introduced a special order for entering Russia. They will be able to enter only either through the border point at "Ludonka" near Pskov, or at Moscow international airport "Sheremetyevo". 
This measure is introduced temporarily to ensure the safety of citizens during the current geopolitical situation. 

Previously the president of Russia issued a decree under which Ukrainian citizens can enter Russia visa-free with the following documents:
- passport of the citizen of Ukraine;
- passport of the citizen of Ukraine for exiting Ukraine;
- diplomatic passport;
- birth certificate for children under 16.
In case any of the documents is expired, it can still be used to enter Russia.
The decree took power from September 29th. You can find the text of it available in Russian here.