Well, how 'bad' it is depends on who you are talking to in what context! I'm sure that the prime minister - and anyone else - would use the word 'bastard' informally and 'off the record', but I would agree with you that it isn't an appropriate style of language for a press conference. It's clear that he wanted to show his strong feelings about these people, but a native English speaker in the same position (eg a British or American head of state) would not have used this word.

It depends on the context. "Bastard" means a child out of wedlock, so it is an actual word. We also say things like "bastardized [something]" to describe when something is corrupted. For example, we say "bastardized English" to describe English that is not grammatical or riddled with slang.

It is nowhere near the worst of insults in English, but I am also surprised to hear him say that!

This is considered a 'bad word', however it isn't as bad as many others. I'm surprised to hear it used in a press conference, but given the circumstances it isn't nearly as bad as many other words he could have selected. Best not to use this word in conversation unless you're amongst close friends, I'd say. Maybe others can provide some more helpful context? cee

"Bastard" is cultural minefield. How bad a word is it? It depends on the context, how it is said, and which of its many meanings it has. I couldn't find the audio, but apparently Yatsenyuk called for international support "to bring to justice all these bastards who committed this international crime." He shows how strong his feelings are by letting his language get SLIGHTLY out of control and go SLIGHTLY out of bounds. "Bastard" is not taboo, it is not vulgar, it is standard English. However, its main meaning is a disagreeable, mean, offensive, cruel person. If it is said seriously, it is a bad insult. Like other bad insults, it CAN also be a friendly joke. "What, you've got tickets to that concert? You lucky bastard!" To make things more complicated, it has a perfectly straight meaning of "small" or "not standard size." There is a carpenter's tool called "a bastard file." It has the meaning "illegitimate," meaning a child born to a couple who are not married--often, a married man's child born by a woman who is not his wife. By extension, it can mean anything mixed up in an incorrect way. So, there is a perfectly acceptable word, "bastardized," meaning something corrupt or debased. "Real Greek yogurt is good, but watch out, there are a lot of bastardized versions of Greek yogurt in the supermarket today."