INSTANT VIEW - Mueller impanels Washington grand jury in Russia probe

Donald Trump Jr. (L) talks with his father, Republican Presidential candidate Donald Trump during the 2016 Republican National Convention in Cleveland, Ohio U.S. July 20, 2016. REUTERS/Jim Young

NEW YORK (Reuters) - Grand jury subpoenas have been issued in connection with a June 2016 meeting that included President Donald Trump's son, his son-in-law and a Russian lawyer, two sources told Reuters on Thursday, in a sign that special counsel Robert Mueller's investigation is gathering pace.

The sources added that Mueller had convened a grand jury in Washington to help investigate allegations of Russian meddling in the 2016 U.S. election.