President Donald Trump must be willing to confront Russia's Vladimir Putin during their summit Monday in Helsinki, Republican Sen. John McCain says.

McCain says that if Trump is not prepared to hold Putin accountable, the summit should not take place.

McCain's statement comes after the Justice Department announced charges Friday against 12 Russian intelligence officers accused of hacking into Democratic accounts during the 2016 presidential election.

McCain says the revelations from the Justice Department add to a body of evidence that confirms a Russian plot to "attack the 2016 election, sow chaos and dissension among the American electorate, and undermine faith in our democracy."

In response to the indictment, Democrats overwhelmingly called for Trump not to meet with Putin. The news release from McCain's office adds a rare GOP name to that list.

The Kremlin has denied that the Russian state interfered in the U.S. election.