The Senate intelligence committee says it will subpoena two of former national security adviser Michael Flynn's businesses.
The committee has already subpoenaed Flynn for documents regarding his contacts with Russian officials during the 2016 presidential campaign. Flynn has refused to hand over that information.
The committee also sent a letter to Flynn's attorney Tuesday questioning the legal basis of Flynn's decision to invoke his Fifth Amendment right over a request for documents rather than testimony.
Committee Chairman Richard Burr says senators will wait for Flynn's response to Tuesday's requests before they decide the next course of action, including the possibility of a contempt of Congress citation.
The committee is investigating Russia's campaign meddling and possible ties to President Donald Trump's associates.