He said this in an interview with Austrian Der Standard, Censor.NET informs citing the press service of the U.S. Embassy in Ukraine.
Pyatt named some substantial changes since Yurii Lutsenko's taking office of the prosecutor general, which include the creation of the National Anti-Corruption Bureau and the post of the anti-corruption prosecutor.
"The new Prosecutor General Yurii Lutsenko has a very good relationship with us. A former prosecutor from the U.S. Department of Justice works as his advisor, which President Petro Poroshenko asked for. There are also EU officials who are working in the office of Lutsenko. The Ukrainian civil society is fighting more actively against corruption than ever before," Pyatt said.
He stressed that it still had to happen that people had to go to jail and someone was held accountable. He said it was "a big step forward" on Wednesday when Lutsenko opened an indictment against MP Oleksandr Onyschenko, who is under suspicion of corruption.
The ambassador also noted that Ukrainian oligarchs are not as influential now as they used to be several years ago.
"The oligarchs have become less powerful. We had this problem in the United States in the early 20th century with, for example, the Rockefellers and Carnegies, but we managed to get this problem under control. Ukraine is just starting that process - and it will take time," he added.
Pyatt noted that Ukrainian society no longer accepts corruption unquestioned, and the media have become much more active. Despite many media being still owned by large companies, there are now alternatives, the ambassador said.