The subpoena from the Republican-led committee comes after Senate Majority Leader Mitch McConnell said its time to call "case closed" for the investigations on Russian Federation.
John Cornyn, a member of Senate Intelligence Committee who is up for re-election next year, just told CNN's Manu Raju he understands Trump Jr.'s frustration with the panel and says the committee probe is "wearing kind of thin".
He said the committee reserves the right to call witnesses back if they see inconsistencies in testimony. Burr's office has also not replied to requests for comment from Breitbart News as to why he issued this subpoena despite McConnell's orders that the case was closed.
Trump Jr. has already testified under oath in 2017 before both the House and Senate intelligence committees and the Senate Judiciary Committee.More news: China says ready to defend trade interests
Warner said his panel knew about "90 to 95 per cent" of the Russian contacts mentioned in Mueller's report, and in other areas the committee had "much more extensive" information. Richard Burr, North Carolina Republican and the panel chairman, was a lapdog for the committees Democratic minority led by Sen.
In an interview with CBS News, Mulvaney said it was "bad form" for the Republican-led committee to subpoena Trump Jr. without giving him advance notice.
Mueller had nearly studied for two years whether or not there was collusion of trump's campaign team with Russian Federation, and whether the US President of the obstruction of Justice is guilty. The committee has recently begun re-interviewing witnesses, including Trump's son-in-law, Jared Kushner, who appeared for a second time earlier this year.
The pair pursued a potential tower in Moscow well into the 2016 presidential campaign - Cohen has said he regularly briefed members of the Trump family of their progress - but nothing came of it. Rick Gates, Manafort's former deputy who was charged and pleaded guilty in the special counsel's investigation, told Mueller's team about the discussion.
Trump Jr. testified for more than 25 hours before the Senate Judiciary Committee in September of 2017 that he had little knowledge of plans for a Trump hotel in Moscow. "Ultimately, it was Michael Cohen essentially trying to get a deal done".