Even the Security Council has limited usefulness in a confrontation like this, because decisions are so politicized. The case of Bucha is a great example. When reports of atrocities first came out, it was Russia who requested the UN to launch a commission of inquiry into Bucha, and it was the UK, who held the presidency of the Security Council at the time, that blocked it. This was reported in Ukrainian news. (https://frontnews.eu/en/news/details/25750)