U.S. intelligence picked up conversations of Russian government officials discussing associates of President Trump as early as 2015, months before he declared his candidacy, according to a report Wednesday.

The Wall Street Journal reported American intelligence agencies overheard Russians talking about meetings outside the U.S. involving Russian government officials and Trump business associates or advisers.

Current and former U.S. officials told the paper the identities of the Trump associates or advisers is unclear, and it's unknown whether any had connections to his presidential campaign.

The intelligence agencies initially were unsure how to interpret the conversations, which were collected as part of routine monitoring of Russian espionage. The monitoring did not directly target the Trump associates or advisers, the Journal said.

But in light of the recent revelations that Trump's eldest son, Donald Trump Jr., met with a Russian attorney in June 2016 who promised damaging information on Hillary Clinton, the intelligence agencies are returning to the intercepted 2015 messages to try to interpret them.

The Wall Street Journal said the conversations picked up in the 2015 monitoring were not particularly illuminating. Trump had business connections in Russia, and sold properties to Russians, so it's possible these conversations were unrelated to the election, the Journal acknowledged.

But they add another dimension to various congressional investigations, and a probe by special counsel Robert Mueller, of Russia's election interference and the possibility the Trump campaign worked with the Kremlin.