SEOUL, South Korea -- North Korean leader Kim Jong Un threatened to expand his nuclear arsenal and develop more sophisticated atomic weapons systems, saying the fate of relations with the United States depends on whether it abandons its hostile policy.
Kim's comments made Friday during a key ruling party meeting was seen as an effort to apply pressure on the incoming government of President-elect Joe Biden, who is to take office later this month.
The Korean Central News Agency said today that Kim says "key to establishing new relations between [North Korea] and the United States is whether the United States withdraws its hostile policy" on North Korea.
Kim said he won't use his nukes unless "hostile forces" intend to use their nuclear weapons against North Korea first. But he said North Korea must further strengthen its military and nuclear capability as the danger of a U.S. invasion on North Korea increases.
Kim ordered officials to develop missiles with multiple warhead, underwater-launched nuclear missiles, spy satellites and nuclear-powered submarines.
The Korean Central News Agency said Kim's order was made during a fourth-day meeting Friday of his country's first ruling party congress in five years.
On Thursday, Kim had stressed the need to drastically improve his nation's ties with the outside world.
State media said Kim also reviewed relations with rival South Korea but didn't explain what steps he said he wanted to take. Observers have expected Kim to use the first congress of the ruling Workers' Party in five years to send conciliatory gestures toward Seoul and Washington as he faces deepening economic troubles at home.
In his speech on the third day of the meeting Thursday, Kim "declared the general orientation and the policy stand of our party for comprehensively expanding and developing the external relations," the Korean Central News Agency said Friday.
Kim also examined relations with South Korea "as required by the prevailing situation and the changed times," the news agency said.
The congress is the party's top decision-making body that reviews past projects, lays out new priorities and reshuffles top officials. It was convened as Kim struggles to overcome what he calls "multiple crises" caused by an economy battered by pandemic-related border closings, a series of natural disasters and U.S.-led economic sanctions.
In his opening-day speech, Kim admitted his previous economic plans had failed and vowed to adopt a new five-year development plan. On the second day of the meeting, he said he would bolster his country's military capability.
Kim, who inherited power upon his father Kim Jong Il's death in late 2011, turned 37 on Friday. His birthday hasn't yet been designated a national holiday like his father's and grandfather's.
After a provocative run of weapons tests in 2016-17 to acquire the ability to strike the U.S. mainland with nuclear weapons, Kim abruptly launched high-stakes nuclear diplomacy with President Donald Trump, which awarded him long-desired legitimacy on the world stage. He also met Chinese, Russian, South Korean and other world leaders. But as his diplomacy with Trump stalled and the coronavirus forced him to close his country's borders, Kim has been focusing domestically to mitigate the economic shocks from the pandemic.
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," the Korean Central News Agency said.
Ties between the Koreas once flourished after Kim entered talks with Trump. But North Korea has halted exchanges with the South and resumed harsh rhetoric against it since the breakdown of the Kim-Trump summit in Vietnam.