The Senate Intelligence Committee has subpoenaed President Trump’s son, Donald Trump Jr., over matters related to the Russia investigation, Axios reports. It’s the first known congressional subpoena of one of Trump’s children. Don Jr. told the Senate Judiciary Committee last year that he was only “peripherally” aware of the Trump Tower Moscow project, which was in its nascent stages in 2015—the same year Trump announced his presidential campaign. However, Trump’s former personal attorney Michael Cohen told the House Oversight Committee earlier this year that he briefed Don Jr. and Trump’s daughter Ivanka on the project about 10 times during the campaign. In a statement, a Senate Intel spokesperson told Axios that they “do not discuss the details of witness engagements with the Committee.”