US President Donald Trump has said his eldest sons controversial meeting last year with a Russian lawyer counted as "opposition research".
Speaking at a news conference during a visit to Paris, Mr Trump said "most people" would have taken the meeting.
Emails show the presidents son and two top campaign officials met the Russian attorney during the campaign.
A Senate panel is asking Donald Trump Jr to publicly testify about the meeting.
Chuck Grassley, the Republican chairman of the judiciary committee, said he would issue a subpoena, compelling the presidents son to testify, if necessary.
Several congressional committees and a special counsel are investigating alleged Russian efforts to influence last Novembers US election and whether Trump aides colluded.
Flanked by French President Emmanuel Macron, President Trump said on Thursday: "From a practical standpoint, most people would have taken that meeting.
"Its called opposition research or even research into your opponent."
Mr Trump twice referred to his son, who at 39 is the same age as Mr Macron as "a young man".
"My son is a wonderful young man. He took a meeting with a Russian lawyer, not a government lawyer but a Russian lawyer," Mr Trump said, in response to the first question he was asked by journalists at the news conference.
"Ive had many people call up Oh, gee, we have information on this factor or this person, or frankly, Hillary - thats very standard in politics.
"Politics is not the nicest business in the world, but its very standard, where they have information and you take the information," he said, blaming the press for inflating the significance of the story.
"Nothing happened from the meeting. Zero happened," Mr Trump insisted.
Mr Trump Jr was joined by the presidents son-in-law, Jared Kushner, and then-campaign manager Paul Manafort, in meeting Natalia Veselnitskaya at New Yorks Trump Tower on 9 June 2016, as Donald Trump Snr closed in on the Republican nomination.
The lawyer, who US media report has ties to the Kremlin, was said to be offering damaging information to provide to the Trump campaign regarding Hillary Clinton.
The documents "would incriminate Hillary and her dealings with Russia and would be very useful to your father", according to the email sent to the presidents son by British music promoter, Rob Goldstone.
Mr Goldstones email added: "This is obviously very high level and sensitive information but is part of Russia and its governments support for Mr Trump."
"If its what you say, I love it," the presidents son responded.
Ms Veselnitskaya denies having ever worked for the Russian government. Donald Trump Jr told Fox News the meeting was "such a nothing" and described it as a waste of time.
During the event in Paris, Mr Trump also blamed members of the Obama administration for allowing Ms Veselnitskaya to be admitted into the United States.
Also on Thursday, a spokesman for US Vice-President Mike Pence said his boss "had no meetings with any individual associated with the Russian government during the campaign or transition" into the White House.
The denial comes after a Fox News interview on Wednesday in which Mr Pences spokesman ducked a question three times on whether Mr Pence had attended any such meetings.