Kim's comments during a key meeting of the ruling party this week were seen as applying pressure on the incoming administration of President-elect Joe Biden, who has called Kim a "thug" and has criticized his summits with President Donald Trump.
"He appears to be gauging how to set relations with the Biden administration based on what they see as a self-defensive nuclear deterrent", Prof Yang said.
Washington's hostile policies would not change regardless of who occupies the White House but dropping those policies would be key to North Korea-U.S. relations, Kim said, according to state news agency KCNA.
"Our foreign political activities should be focused and redirected on subduing the U.S., our biggest enemy and main obstacle to our innovated development", Kim said during nine hours of remarks over several days at a rare party congress in Pyongyang.
Mr Kim did not cite any specific provocative United States actions.
Biden, who will take office on January 20, is unlikely to hold direct meetings with Kim unless the North Korean leader takes significant denuclearization steps.
The eighth congress of the ruling Workers' Party came amid a prolonged gridlock in negotiations aimed at dismantling North Korea's nuclear and missile programmes in return for U.S. sanction relief.
The programs have made rapid progress under Mr Kim, including by far its most powerful nuclear blast to date and missiles capable of reaching the entire continental United States, at a cost of increasingly stringent global sanctions.
He said that plans for a nuclear submarine were nearly complete.
Mr Kim called for more research and development of advanced military equipment, including spy satellites, hypersonic weapons, solid-fuel intercontinental ballistic missiles and reconnaissance drones.
"The reality is that we can achieve peace and prosperity on the Korean Peninsula when we constantly build up our national defence and suppress United States military threats".
North Korean leader Kim Jong Un stressed the need to drastically improve his nation's ties with the outside world as he addressed a major political conference for the third day.
Despite a self-imposed moratorium on nuclear and ICBM testing in 2018, North Korea continued to beef up its weapons programmes, unveiling what was deemed its largest ICBM yet at a parade in October. In particular, the North views the U.S.
"The report made a stern warning that we will have no choice but to treat the South differently if it continues to push us to the corner citing 'provocations, '" it said.
Inter-Korean relations made some headway around 2018 summits but have soured as the nuclear talks made little headway.
During Thursday's session, Kim also called for "thoroughly eliminating non-socialist elements" in North Korean society and proposed ways to promote the "might of the social system of our state".
North Korea has not responded to Seoul's offers for talks and cooperative projects, while focusing on warding off an outbreak of the coronavirus on its soil by sealing its border and toughening quarantine measures. Kim's state media have said those sanctions are "strangling and stifling our country" and are proof of USA hostility.
Besides US and defence policy, Mr Kim also spoke at length on proposals for a new five-year economic plan due to be announced at the congress, which he said would continue a focus on building an independent economy.
"The basic seeds and themes of the new five-year economic development plan are still self-reliance and self-sufficiency", he said. Typhoons and floods have devastated homes and crops in North Korea, which remains under strict worldwide sanctions, including over its nuclear programme.
This file picture taken on January 6, 2021 and released from North Korea's official Korean Central News Agency (KCNA) on January 7, 2021 shows North Korean leader Kim Jong Un speaking during the second day of the 8th Congress of the Workers' Party of Korea (WPK) in Pyongyang.
KCNA said that a fifth-day session was to be held Saturday.