U.S. Homeland Security Secretary Kirstjen Nielsen has said the United States must be ready to resist attempted Russian interference in the country's elections later this year.

"I don't think there is any question in the [intelligence] community or at [the Department of Homeland Security] that Russians attempted to infiltrate and interfere with our electoral systems," Nielsen said at a security forum in Colorado on July 19.

"I don't think there's any doubt that they did it, and I think we should be prepared given that capability and will, that they'll do it again."

Nielsen added that she had not seen evidence that Russia worked "to favor a particular political party."

"The overall purpose is to sow discord," she said.

Also on July 19, Senate Majority leader Mitch McConnell said he asked two Senate committees to hold hearings on possible additional sanctions against Russia over its alleged election interference.

He said the hearings would be part of a response to election interference by Russia in the upcoming November elections.

On July 16, Dan Coats, the U.S. director of national intelligence, said Russia continued to pose a threat to U.S. electoral systems.

He said Russia was carrying out "ongoing, pervasive efforts to undermine our democracy."

On July 18, President Donald Trump expressed confidence in Coats. "I have tremendous faith in Dan Coats, and if he says that [Russia is a threat], I would accept that," Trump told CBS.

Trump came under harsh criticism from people in both major U.S. parties for his perceived weak responses to questions about Russia's purported interference in the 2016 presidential election during his joint press conference with Russian President Vladimir Putin in Helsinki on July 16.

In January 2017, U.S. intelligence agencies issued a joint conclusion that Russia conducted a state hacking-and-propaganda campaign aimed at influencing the 2016 presidential election in favor of Trump.

With reporting by AP, Reuters, and AFP