"Why stop now? This must be the question Vladimir Putin is asking himself as he considers the latest European pleas for peace in Ukraine, to be discussed at a crisis summit in Minsk on Wednesday."
Since invading and annexing Crimea almost one year ago, the Russian president has been running rings around the European Union, NATO and the Obama administration.
It is not that Putin is particularly clever, on the contrary, his behavior suggests he is paranoid, impulsive and insecure.
But he has benefited from the greater weaknesses of his opponents.
So as he considers his response to Europe's ideas for a new cease-fire and a "comprehensive settlement" in eastern Ukraine, what will Putin be thinking? What does he know?
Read more: Putin knows, for a start, that the Europeans are divided and running scared.