Former White House chief strategist Steve Bannon was subpoenaed last week to testify before grand jury, according to a New York Time article. The subpoena was issued by special counsel Robert Mueller.
The report noted that this is the first time that Mueller has used a grand jury during his investigation into Russia's meddling in the 2016 presidential election.
On Tuesday, Bannon testified before the House Intelligence Committee. His appearance before the committee comes after author Michael Wolff's "Fire and Fury" quoted the former White House staffer.
In the book, Bannon called Donald Trump Jr. and Jared Kushner meeting at Trump Tower with a Russian lawyer "treasonous" behavior.