President Donald Trump initially stated he was not aware of the meeting first son Donald Trump Jr. held in June 2016 with a Russian attorney.
But a remark he made on Air Force One as he flew to Europe appeared to contradict his earlier assertion, according to Think Progress.
Trump was asked July 12 in a Reuters interview whether he had been told about the meeting, which was also attended by his son-in-law Jared Kushner and Paul Manafort, Trump's campaign manager at the time.
"No, that I didn't know until a couple of days ago when I heard about this," said Trump.
Speaking to reporters on Air Force One, Trump said, "In fact maybe it was mentioned at some point."
He stressed that if it had been mentioned, he was not aware that the purpose of the meeting had been to obtain information on the campaign of Democratic nominee Hillary Clinton.
"They talked about the adoption stuff, which was actually a big thing at the time, but nothing happened," Trump added.
Despite such reassurances, members of Congress want to hear more from Trump Jr. about the June 2016 meeting. Sen. Charles Grassley of Iowa, the chair of the Senate Judiciary Committee, told CNN July 13 that he was sending a letter to Trump Jr. requesting that he testify before the committee.
"I think it's just raised a lot of questions," Grassley said. "But the real way that I feel comfortable inviting him is ever since President Trump was elected. It seems like every conversation that has come from somebody in the family where there's been some sort of issue, they've seemed always to be very, very open."
Sen. Dianne Feinstein of California, the top Democrat on the committee, has called for Trump Jr. to testify as early as mid-July.
Grassley is also vowing to get Manafort to testify and said he is cooperating with Feinstein to question Trump's former campaign manager.
"We're working very close on this and we've already agreed that we're going to bring Manafort before our committee," added Grassley, reports the Des Moines Register.
Grassley wants to question Manafort about the enforcement of the Foreign Agent Registration Act, but noted others may take up the issue of his attendance at the June 2016 meeting.
"If he comes before our committee -- and we'll subpoena him if necessary -- then obviously it'd be appropriate for anybody to get into anything that went on at that meeting, since he was at that meeting," Grassley said.