North Korea Supreme Leader Kim Jong-un calls the United States its "biggest enemy" and warns of more nuclear weapons during an important meeting of the Worker's Party last week, reports say.

Jong-un, who is also the Workers Party leader, according to Voice of America, "threatened to expand his nuclear arsenal" and called on former Vice President Joseph Biden to remove its "hostile policy" so as to "establish better ties" with North Korea.

The call was made after Biden during his campaign announced a more "adversarial approach to toward Pyongyang"; frequently referred to Jong-un as a "thug," "tyrant," and "dictator"; and said would only meet face to face with him "as part of broader, working level talks," VOA stressed.

In the same way, Biden, as per VOA News, also often critized President Donald Trump for reaching out to North Korea for their de-nuclearization in an attempt to prevent wars with the United States, referring to it as an "ineffective" effort that is only meant "at creating headlines than addressing the North Korean nuclear issue."

Reuters, on the other hand, reported Trump had three meetings with Jong-un that was followed by "a series of letters" that nonetheless brought "no official change in the countries' relations" nor to a denuclearization effort.

Jong-un's call, as per Reuters, was one of "open cooperation" with the U.S. to drop its "hostile policies" notwithstanding "who occupies the White House" during a nine-hour meeting with the Workers Party, which the media outlet described as a "rare party congress in Pyongyang."

"Our foreign political activities should be focused and redirected on subduing the U.S., our biggest enemy and main obstacle to our innovated development," Reuters quoted Jong-un in saying.

Jong-un, as per Reuters, also vowed to expand its ties with "anti-imperialist, independent forces" although it will not "misuse" its nuclear resources but only intends to expend its current arsenal with "preemptive," "retaliatory" weaponry "of varying sizes" such as "hypersonic weapons, solid-fuel intercontinental ballistic missiles (ICBMs), spy satellites, and drones."

Reuters reported that Jong-un will be getting ready for the testing and production of "multi-warhead rocket" and "supersonic gliding flight warheads for new type ballistic rockets" and will be finishing on their "nuclear submarine" research.

Jong-un also condemned the efforts of South Korea to build better ties with the U.S. through tourism, providing coronavirus, buying arms from the U.S., and conducting military drills with them, Reuters said.

Reuters cited U.S. Diplomat for East Asia under former President Barack Obama, Kurt Campbell, to have announced last December the need for the new U.S. administration to immediately devise its strategy for North Korea so as to avoid the Obama era's delay.

However, Stimson Center North Korea Specialist Jenny Town said, as cited by VOA News, Biden actually has a lot in his hands considering the current political climate and the priorities he set at the moment.

"This is a tall order though, in the current political environment," Town stressed, "There's a lot demanding his time and attention."

"Moves like early appointments of a North Korea policy team, lifting the travel ban (on North Korea), and other types of actions would help demonstrate that a different outcome and relationship is possible with a new administration," she added.