Standing before reporters in February, President Trump said unequivocally that he knew of nobody from his campaign who was in contact with Russians during the election. Attorney General Jeff Sessions has told the Senate the same thing. Court documents unsealed this week cast doubt on both statements and raised the possibility that Mr. Sessions could be called back to Congress for further questioning. For months, journalists have revealed evidence that associates of Mr. Trump met with Russians during the campaign and the presidential transition. But the court documents represent the first concrete evidence that Mr. Trump was personally told about ties between a campaign adviser and Russian officials.