Quote Originally Posted by it-ogo View Post
"вмешаться/вмешиваться" can be negative but not necessarily. Вступиться можно только за кого-либо/что-либо. Вступиться can be used only along with за+object in Accusative (or at least this construction should be implied). It means "intervene to protect someone/something specified against someone/something else." So here it is not applicable.

"Путин успел расстрелять 18 московских гомосексуалистов, пока за них не вступился госсекретарь США."
I thought you could say вступился meaning to step in and break up a fight - but maybe I'm confused.

Anyway, I think it's wrong to translate "intervene" and "interfere" with the same word.

For example the two sentences "The USA often interferes in Middle Eastern Politics" and "The USA often intervenes in Middle Eastern Politics" are not equivalent at all. Or "The USA interfered to resolve the crisis" that just doesn't make any sense - you can't interfere to make something better.

Maybe you could use суется for "interfere".