Censor.NET reports citing Associated Press.
He said Russia possibly meddled in U.S. election but also in that of other countries.
'Nobody really knows for sure,' Trump said.
At a joint press conference with Polish President Andrzej Duda Trump said that President Barack Obama knew of the meddling, as it's been taking place for many years.
U.S. secret services have long been accusing Russia of cyberattacks, including those upon servers of the Democratic candidate Hillary Clinton during the presidential election in 2016. Then-President Barack Obama said that Russian leader Vladimir Putin could have been personally involved in the hacker attack. The Kremlin has been denying its involvement.