From the casting call for episodes 21/22:
[BERKOV] Russian Aide to the Russian Delegate working at the UN in NY. Mid 30s to mid 40s. Must be able to do a slight Russian accent.. Should be more upscale. In Episode 22…NICE CO STAR ROLE
Three days after this casting call was posted, Davoli excitedly tweeted “I BOOKED 24!!!” and on March 22 he posted a message to his Facebook fan group saying “Great time shooting 24 today. Stay tuned for episode #22.”