Russia is already trying to meddle in this year's midterm congressional elections, Secretary of State Rex Tillerson said.
In an interview with Fox News, the former Exxon Mobil CEO casted doubt on whether the U.S. could prevent Russia from causing damage again.
"I don't know that I would say we are better prepared, because the Russians will adapt as well," Tillerson said in the Tuesday night interview. "The point is, if it's their intention to interfere, they are going to find ways to do that."
He added: "This is something that, once they decided they're going to do it, it's very difficult to pre-empt it."
Still, Tillerson said the U.S. should continue warning Russia against election meddling.
"I think it's important we just continue to say to Russia, 'Look, you think we don't see what you're doing. We do see it and you need to stop. If you don't, you're going to just continue to invite consequences for yourself,'" Tillerson told Fox.
The secretary of State's warnings follow similar statements from CIA Director Mike Pompeo, who told BBC News that he expects Russia to target this year's midterm elections.
"I have every expectation that they will continue to try and do that, but I'm confident that America will be able to have a free and fair election (and) that we will push back in a way that is sufficiently robust that the impact they have on our election won't be great," Pompeo told the BBC.
Pompeo also recently met with top Russian intelligence officers, according to CNN.
The U.S. intelligence community has said that Russia interfered in the 2016 general election, which pitted Democrat Hillary Clinton against Republican and eventual winner Donald Trump.
Special counsel Robert Mueller is investigating the extent of Russian involvement, and whether the Trump campaign colluded with the Kremlin during the campaign. Trump has repeatedly denied collusion and called the Russia meddling story a "hoax" perpetrated by Democrats.