ST. LOUIS — Hillary Clinton’s campaign is going on offense now that the U.S. government has backed up its assertion that Russian hackers are meddling with the presidential election.

And with Sunday’s prime-time debate approaching, it’s demanding a response on the diplomatic crisis from Donald Trump, who to date has shrugged off the Russians’ role in the cyber espionage.

“What’s disturbing about the situation is now that we know for certain it was the Russians and it was reported that Donald Trump has been briefed on the matter, that he continued to imply that it wasn’t the Russians, that he continued to effectively deflect any focus or criticism on them,” Clinton’s campaign manager, Robby Mook, told POLITICO on Sunday.

“That’s sort of disturbing that there’s an active espionage happening and he’s somehow shielding them from that. He needs to answer for that, why he did, why he said those things,” Mook added.

Trump and his campaign have gone radio silent regarding Friday’s statement by the Department of Homeland Security and director of national intelligence that Russian President Vladimir Putin’s government ordered up the hackings into various U.S. political organizations, including the Democratic National Committee. That news broke a little more than an hour before the release of an 11-year old video showing Trump bragging about his ability to grab women by their genitals, a controversy that has totally upended his presidential campaign.

While Clinton campaign chairman John Podesta immediately pounced on the Russia hacking news with a statement on the federal government’s decision, there’s been nothing on the topic from Trump. An email Sunday requesting comment from Trump’s campaign office went unanswered.

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Given the importance of the topic in both U.S. and international circles, it is almost certain to be asked about Sunday. And how Trump responds will be contrasted with earlier remarks he made during the first debate, when he downplayed Putin’s role in the hackings.

“She said Russia, Russia, Russia, maybe it was. Could also be China. Could also be somebody sitting on their bed, that weighs 400 pounds,” the Republican said last month.

In the interview, Mook shrugged off Trump’s recent call for his supporters to go to “certain areas” in battleground states for poll watching because the race may be rigged against him.

“The election won’t be rigged,” Mook snapped.

Mook also dismissed Trump’s statement to the New York Times earlier this month backing away from an earlier pledge during the first debate that the Republican would “absolutely” accept the election outcome, even if he loses.

“I’m more focused right now on making sure we win and we win by the biggest margin possible,” Mook said. “Donald Trump is going to say whatever he’s going to say. I think the results will speak for themselves.”