Former White House aide specializing in Russia, Dr. Fiona Hill's hearing for the ongoing impeachment inquiry against President Donald Trump may be closed-door, but news of her testimony is inevitably getting out.

One troubling event to emerge from Hill's testimony is that she was instructed to report the President's personal attorney, Rudy Giuliani to the National Security Council in July. Officials within the Trump administration grew concerned with Giuliani's escalating attempts to pressure Ukrainian officials.

Among them was former National Security Adviser John Bolton, who—according to Hill—said:

"Giuliani's a hand grenade that's gonna blow everybody up."

Months after Bolton's resignation, it seems like his prediction is vindicated: two of Giuliani associates involved in his Ukraine efforts have been arrested on campaign finance violations, Another Giuliani-Ukraine associate is cooperating with the impeachment inquiry, Giuliani is fighting a subpoena, and his television appearances—while entertaining—do nothing to help his or the President's case.

Giuliani soon responded, telling NBC News correspondent Kristen Welker:

“I’m very disappointed that his bitterness drives him to attack a friend falsely...It’s really ironic that John Bolton is calling anyone else a hand grenade. When John is described by many as an atomic bomb."

Bolton reportedly fought with Ambassador to the European Union, Gordon Sondland, who appears to have been working with Giuliani to pressure Ukrainian officials.

Trump fired Bolton last month, citing disagreements with "many of his suggestions."

As far as Bolton's assessment of Giuliani, people agree.

Some are predicting that Hill's testimony will lead lawmakers to subpoena Bolton, who could be all-too-eager to comply.

Hill testified for a total of ten hours, so it's likely more revelations are still to come.