UPDATE: It turns out that even Russia's president Vladimir Putin himself quoted Bismarck as saying that phrase! (Source1, Source2). It thus seems unlikely to be a made-up quotation, because it is unthinkable that the Russian president will use made-up quotations. I am very much curious to find the original German phrase and its context and spent a few more hours searching, but found nothing. That's a real mystery...
Reading an article for my Russian classes, I saw a quotation from Otto von Bismarck:
Но еще Отто фон Бисмарк сказал: "Меня не интересуют их намерения, меня интересуют их возможности". (Source)
The quotation as it stands in Russian is so ruthless, cynical, and thought-stimulating that I got really curious what Bismarck actually said in German and whether he said anything like that at all.
I did a lot of research and was unable to find any trace to the German original, but found that the above quotation is very frequently used in the Russian language as an aphorism attributed to Bismarck, as there are hundreds of hits in Google, quite a few hits in Google Books, and even a hit in minutes of the Russian Parliament. There are also rephrasings, e.g.:
... но еще Бисмарк сказал: "В политике важны не намерения, а возможности. Намерения меняются, возможности остаются". (Source)
I have been unable to find any similar aphorism in German, English, or Japanese. I even asked a question on the German SE and a question on the History SE in an attempt to find the original German phrase by Bismarck, but no one has been able to help me so far. For some mysterious reason this aphorism appears to be popular exclusively in the Russian language.
My question is this: What is the actual origin of this Russian aphorism attributed to Bismarck?