His refusal to back down is rooted in Russia’s gangster politic
back down
to take back a demand, an opinion, etc. that other people are strongly opposed to; to admit defeat 放弃（别人强烈反对的要求、主张等）；认输
She refused to back down on a point of principle.
她在一个原则问题上拒绝让步
On August 29th at a university in Moscow, Vladimir Putin observed that orcas feed on polar bears.
feed
[I] (of a baby or an animal 婴儿或动物) to eat food 进食
Slugs and snails feed at night.
蛞蝓和蜗牛夜间进食
“That’s the food chain,” Russia’s president stated. “Children should be taught about this, so that they understand what kind of world we live in and why we are conducting the special military operation”—ie, Russia’s war on Ukraine. The claim was fanciful: there is no known case of an orca eating a polar bear. But it provided insight into the Russian president’s predatory worldview
ie = i.e.
used to explain exactly what the previous thing that you have mentioned means (from Latin ‘id est’) 也就是，亦即（源自拉丁文 id est）
the basic essentials of life, i.e. housing, food and water
生活的基本需要，即住房、食物和水