That is revealing. Trump realises he can't plausibly cut Giuliani loose, but he wishes he could, because he sees that he is in huge trouble. So he is stuck in the limbo of his I don't know answer, as if that is an anything place to be.
It appears that the Ukrainian two were Giuliani's paymasters in the Trump protection racket. And they appear to have been paid by one of Putin's oligarch goons, Dmitry Firtash. They are closing in on the corrupt connections Mueller couldn't find.
http://twitter.com/SethAbramson/status/1182808252469387264