CIA Director Mike Pompeo warned last month that he does in fact expect Moscow to try to interfere, as US intelligence agencies insist it did in the 2016 presidential election to help Donald Trump beat Hillary Clinton.
Tillerson, speaking to Fox News during a tour of Latin America, said "there's a lot of ways that the Russians can meddle in the elections, a lot of different tools they can use."
"And we are seeing certain behaviors. There are a number of important elections in this hemisphere this year, and leading up to the US in 2018," Tillerson said.
He added, though, that if Moscow decides to meddle in an election, "it's very difficult to preempt it."
Special prosecutor Robert Mueller and US lawmakers are probing the Russian meddling in the 2016 presidential election, specifically whether the Trump campaign colluded in that effort and whether Trump has tried to obstruct justice by hindering the investigations.