The House committees investigating President Trump and Ukraine have requested that Trump's former Russia adviser Fiona Hill appear for a deposition on Oct. 14, as well as turn over several documents dating back to January 2017.

Context: Hill left her role as Trump's top Russia aide in August, although she had wrapped up most of her work by mid-July. It's unclear how much she knew about the controversial July 25 call between Trump and Ukrainian President Volodymyr Zelensky, which is at the center of Democrats' impeachment inquiry.

Hill, a long-standing policy expert and critic of Russian President Vladimir Putin, served under both H.R. McMaster and John Bolton on the National Security Council.

What to watch: The White House made it clear in a letter to House Democratic leaders on Tuesday that it has no plans to cooperate with the committees' interview or document requests.

It was unclear as of Wednesday evening whether the Trump administration plans to block Hill from complying.

Hill could not immediately be reached for comment.