Travel to Ukraine

The easiest way:

1. Fly to Warsaw.
2. Overnight train to Kyiv. The paper ticket needs to be picked up. It leaves Warszawa Wschodnia (Warsaw East Train Station) at 17:48 and arrives at Kyiv at 11:00 the next day. It costs $70 for a two-person cabin that is like a mobile office.  

Return:

1. Overnight train to Warsaw (Kyiv to Warszawa Wshodnia). Train 067K leaves at 19:26 and arrives at 10:12 the next day. It appears difficult to book a ticket for 067K. One can book a ticket of 023K from Kyiv to Chelm, Poland departing at 23:52 and arriving at 12:35, then take a train from Chelm to Warsaw.
2. Fly back.