National security adviser John Bolton briefs the media on election interference at the White House on Aug. 2. (Mark Wilson/Getty Images)

U.S. officials are concerned that not only Russia but also China, Iran and North Korea will try to interfere in this fall’s midterm elections, national security adviser John Bolton said Sunday.

“Well, I can say definitively that it’s a sufficient national security concern about Chinese meddling, Iranian meddling and North Korean meddling that we’re taking steps to try and prevent it,” Bolton said on ABC News’s “This Week” when asked about a tweet by President Trump saying that “all the fools” are focused on election interference by Russia alone. “So all four of these countries, really.”

Bolton said elections are not the only potential targets for hostile international hackers, and he cited a “whole range of vulnerable systems” in both the government and the private sector.

“What we want is not war in cyberspace, we want peace in cyberspace,” he said. “And to do that, I think you need to establish structures of deterrence so that our adversaries who have conducted cyber operations against us or who are contemplating it come to understand they will pay a much higher price if they do that than if they simply refrain.”

Bolton is currently in Israel. He is set to head to Geneva and Ukraine for talks on Russia, North Korea and Syria.

He also said Sunday that Secretary of State Mike Pompeo will travel to Pyongyang “soon” for his fourth visit in recent months, one of them a secret trip disclosed after the fact and the past two accompanied by a handful of journalists. Bolton said the administration expects that Pompeo will meet with North Korean leader Kim Jong Un, who did not grant an audience to Pompeo during his last visit there.

The purpose of the visit will be to urge progress on negotiations to denuclearize North Korea. Bolton said the administration expects it to happen within a year.

“This is to fulfill the commitment that Kim Jong Un made in Singapore, that he had previously made to the South Koreans, and to move on with the process of denuclearization [that] remains our highest priority,” Bolton said, referring to the June meeting between Trump and Kim in Singapore.