(Reuters) - U.S. Homeland Security Secretary Kirstjen Nielsen on Thursday said the United States needed to be prepared for an attempt by Russia to interfere in elections in all 50 U.S. states this year, adding that there was no question Moscow interfered in the 2016 U.S. presidential contest.

“I don’t think there’s any question in the intel community or at DHS that Russians attempted to infiltrate and interfere with our electoral system,” she said. “I don’t think there’s any doubt that they did it, and I think we should all be prepared given that capability and will -- that they’ll do it again.”

President Donald Trump this week has struggled to quiet an uproar over his failure to confront Russian President Vladimir Putin over Moscow’s meddling when the two leaders met in Helsinki on Monday.

At the summit, Trump refused to blame Putin for the election meddling and said it could be “other people,” then a day later tried to clean up his remarks. Earlier on Thursday, Trump said he looked forward to meeting again with his Russian counterpart.

U.S. intelligence agencies have concluded that Russia carried out a campaign of hacking and propaganda targeting the 2016 U.S. presidential election in an attempt to sow discord, disparage Democratic candidate Hillary Clinton and aid Republican Trump’s candidacy. Putin has denied any such meddling.

The U.S. Department of Justice and Congress are investigating the interference and any possible collusion by Trump’s campaign. Trump has repeatedly denied there was any collusion.

Nielsen, at the Aspen Security Forum in Colorado, was asked about the U.S. intelligence community’s assessment that Putin directed the campaign to favor Trump, said:

“I haven’t seen any evidence that the attempts to interfere in our election infrastructure was to favor a particular political party. I think what we’ve seen on the foreign influence side is they were attempting to intervene and cause chaos on both sides.

“The overall purpose is to sow discord.”