SEOUL, South Korea (AP) — North Korean leader Kim Jong Un has threatened to expand his nuclear arsenal and develop more sophisticated atomic weapons systems in response to what he calls American 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.

The Korean Central News Agency said Saturday that Kim says the “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 says North Korea must further strengthen its military and nuclear capability as the danger of a U.S. invasion on North Korea increases.