NOT MANY non-Russians know Russia as well as Oleksandr Lytvynenko. Ukraine’s new national security chief spent five formative years in Moscow as a cryptology cadet at the elite KGB Academy. More recently, as head of Ukraine’s foreign-intelligence service during two years of war, he busied himself undermining and extracting information from his one-time peers. At the end of March, he took over one of the country’s most critical jobs.