U.S. officials can’t stop Russian President Vladimir Putin from interfering in the 2018 elections if he chooses to do so, according to Secretary of State Rex Tillerson.

“If it’s their intention to interfere, they’re going to find ways to do that,” Tillerson told Fox News late Tuesday while traveling in Colombia.

The prospect of election interference has been a point of contention between the United States and Russia, as well as congressional Democrats and President Trump’s administration for much of his first year in office. FBI Director Christopher Wray has established a task force to prevent a repeat of the 2016 cyberattacks against the Democratic Party, but Tillerson pointed to various forms of "consequences" as the chief deterrent.

"I think it’s important we just continue to say to Russia, look, if you think we don’t see what you’re doing, we do see it," he said. "You need to stop. If you don’t, you’re going to just continue to invite consequences for yourself."

Trump’s critics insist they haven’t done enough. “I’m stunned by the administration’s utter failure to respond to these attacks,” New York Rep. Eliot Engel, the top Democrat on the Foreign Affairs Committee, said Tuesday. “Between the President’s constant denial of Russia’s involvement and his constant attacks on our own justice system, you could almost conclude that he would be fine with a repeat of what we saw in 2016.”

Wray told lawmakers in November that he is coordinating with the Department of Homeland Security to pre-empt future cyberattacks. “We’re trying to get in front of it and figure out and be on the lookout for efforts to interfere going forward,” he said during a House Homeland Security Committee hearing.

Tillerson emphasized the limits of such defenses. “I don’t know that I would say we’re better prepared, because the Russians will adapt as well,” he said during the interview. “And we can take steps we can take, but this is something that once they decide they’re going to do it, it’s very difficult to pre-empt it.”

Engel faulted the administration for not implementing a sanctions law passed last summer. “The law singles out those responsible for cyber-crimes,” he said. “It goes after the military and intelligence sectors that drove this attack. Yet the Trump administration has not imposed a single sanction related to election interference mandated by the law.”

The State Department took a step towards implementing that law last week, when they released a report identifying Putin’s closest and wealthiest associates in Russia. U.S. officials also announced that sanctions targeting Russian defense and intelligence sectors were already having an effect, though they didn’t use those provisions against any specific companies.

“The fact that we did not impose sanctions on the very first day that we had authority should, by no means, be interpreted as evidence that we will not impose sanctions in the future,” State Department spokeswoman Heather Nauert told reporters.