By Will Ripley, Tim Schwarz and Ben Westcott CNN

PYONGYANG, North Korea (CNN) -- A North Korean government official in a rare interview promised his country's nuclear tests would "never stop" as long as the US continued what they viewed as "acts of aggression."

Speaking to CNN Tuesday, Sok Chol Won wouldn't confirm when the country's long-anticipated sixth nuclear test would take place but said it wouldn't be influenced by outside events.

"The nuclear test is an important part of our continued efforts to strengthen our nuclear forces," he said.

"As long as America continues its hostile acts of aggression, we will never stop nuclear and missile tests."

Sok's official title is director of North Korea's Institute of Human Rights at the Academy of Social Sciences, but he was authorized to comment to CNN on all matters.

Another nuclear test could further inflame an already tense situation on the Korean Peninsula, at a time when the Trump administration is moving large amounts of military hardware to the region.

The USS Vinson aircraft carrier is currently on its way to the peninsula, while a nuclear-powered submarine, USS Michigan, arrived in a South Korean port on Tuesday. And the THAAD anti-missile system designed to mitigate the threat of North Korea's missiles will be operational "in the coming days," the top US commander in the Pacific said.

Sok said Tuesday's massive artillery drill, held on the 85th anniversary of North Korea's army, was a warning to US President Donald Trump.

"This exercise is a direct response to acts of aggression by the United States," he said.

Reports of human rights abuse 'fiction'

When asked about the three US citizens currently held in North Korean custody, including Kim Sang Duk who was arrested on Saturday, Sok only said they were being kept in the same conditions as other prisoners.

He strongly denied statements made by defectors of brutal North Korean prison camps, where up to 120,000 men, women and children are believed to be held.

"Those people (defectors) are criminals who ran away, they're paid to lie and encouraged by the US and their followers," he said.

"The UN wants to politicize the human rights issue, use it to interfere with our internal affairs. Their reports are nothing but fiction."

Sok said human rights meant defending North Korea and its supreme leader Kim Jong Un, even if it meant nuclear war.

TM & © 2017 Cable News Network, Inc., a Time Warner Company. All rights reserved.