Mr Vorontsov, Head of Department of Korean and Mongolian Studies, Institute of Oriental Studies, visited North Korea in mid-November previous year.
Any attack would need to destroy North Korea's nuclear and missile programs as well as conventional weapons such as long-range artillery and rocket launchers aimed at Seoul, he said.
North Koreans are also genuinely anxious the United States could launch a preventive war on the peninsula.
"By conducting different military actions, one of the objectives that the USA might have is to drive a wedge between political leaders and military leaders inside North Korea", he added.
He said: "These officials were truly baffled that a majority of the South Korean population does not seem to have grasped the reality that the Trump administration, despite the risks, is inching ever closer to a preventive strike on North Korea".
According to him, North Koreans officials believe the US public opinion is inching closer to supporting a pre-emptive strike because they fear Pyongyang would attack the U.S.as soon as it had the opportunity to do so-a serious misperception, one diplomat told Vorontsov.
President Donald Trump suggested that a "pretty Korean lady", a career intelligence analyst who was discussing an impending hostage situation in Pakistan with him in the Oval Office, be reassigned to North Korea.
But diplomats also said they are not completely knowledgeable of how North Korea could achieve nuclear parity with a powerful United States. "Only our leader knows the issue in full, '" they said, according to Vorontsov.
But despite the tensions between Washington and Pyongyang, the two Koreas held their first talks in two years on Tuesday and agreed to meet again.
Yonhap reported Thursday North Korea's religious council strongly condemned a U.S. State Department designation of the regime as a country of particular concern under the International Religious Freedom Act.