Times has to go to Russia under the terms of the 1989 agreement. All the new nation states that became autonomous agreed that if they couldn’t govern themselves they’d return to Russia
Crimea was not part of Ukraine under this. It had its own leaders. And in 2014 they had a full on corrupt government and the ethnic Russians in the crimea started uprising. The corrupt government just vacated. Crimea reverted to Russia.
Ukraine been kissy about it. The ethnic Russian population wants back with the motherland.