Провокатор: plant, rabble-rouser, troublemaker, provocateur
One of my favorite new language toys is Google's Ngram Viewer, which lets you — in highly technical Googlese — "search lots of books" to find the frequency of a word or phrase. This is a helpful tool for translators who are trying to choose a word in English that matches, more or less, its Russian equivalent in frequency of usage.
Take, for example, провокатор and provocateur. They are both originally from Latin and mean a secret agent who foments violence or encourages commission of a crime, although the Russian word can refer more generally to anyone who incites enmity or causes trouble. When I'm sitting in my kitchen shooting the breeze with my friends, I have occasionally used the word провокатор. But "Pass the salt and don't be a provocateur"? You didn't hear it from me.
Because language use is so individual, I checked провокация-провокатор and provocation-provocateur on the magic Ngram, searching from 1500 to 2008, its latest search year. Not surprisingly for anyone who knows history, in Russian провокация usage peaks in the 1930s, jumps up a bit in the early 1950s and then starts heading up off the charts in the 21st century. Провокатор has a huge peak in the late 1930s and a minor one in the late 1990s.
In English, provocation frequency peaked in the late 1700s and then has gone straight downhill since then. Provocateur usage jumped up in what looks like the World War II years and then had a tiny bump in the 1980s before heading south.
In other words, translating провокатор as provocateur and провокация as provocation may be technically correct in many contexts, but today the English words are marked and unusual in a way that the Russian words are not.
So how the heck do you translate all these провокации and провокаторы that everyone is talking about today?
Sometimes I like to change the noun провокация into English verb phrases, particularly in everyday contexts. When a guest around the dinner table raises a topic guaranteed to get everyone's blood racing, in Russian you might say: Это провокация. Не реагируйте. (He's just trying to get a rise out of you. Don't react.) But this also works with more official pronouncements: Он заявил, что попытка прорвать полицейское оцепление — спланированная заранее провокация. (He said the attempt to break through police lines was planned ahead of time to provoke a violent reaction.)
Sometimes, however, you don't have to fiddle with the grammar, particularly if the word провокация is modified with an adjective. Псевдо-избиение Тимошенко — это политическая провокация, которая была разработана соратниками (The pseudo-beating of Tymoshenko is a political provocation arranged by her associates).
When translating провокатор, I think provocateur only works well in certain historical contexts. Гапон: революционер или провокатор царской охранки? (Father Gapon: revolutionary or agent provocateur for the tsarist secret police?)
Otherwise, I try to stick to more commonly used words and phrases. Кидали камни не демонстранты, а провокаторы (Stones weren't thrown by the demonstrators, but by plants in the crowd.) В толпе полицейские провокаторы начали беспорядки (Undercover police operatives in the crowd started the riot).
In less politically fraught circumstances, провокатор might be a troublemaker or someone trying to get your goat. Не обращай на него внимание! Он просто провокатор (Don't pay any attention to him. He's just goading you.)
Calm down and pass the salt.