Stephen K. Bannon, President Trump’s former chief strategist, was subpoenaed last week by the special counsel, Robert S. Mueller III, to testify before a grand jury as part of the investigation into possible links between Mr. Trump’s associates and Russia, according to a person with direct knowledge of the matter.
The move marked the first time Mr. Mueller is known to have used a grand jury subpoena to seek information from a member of Mr. Trump’s inner circle. The special counsel’s office has used subpoenas before to seek information on Mr. Trump’s associates and their possible ties to Russia or other foreign governments.
