North Korea has pledged its "strongest response strategy" against the US during a key year-end party meeting, media reports said on Sunday.

The Central Committee of the Workers' Party of Korea convened from Monday to Friday, with North Korean leader Kim Jong-un presiding, the Yonhap News Agency quoted the Korean Central News Agency (KCNA).

The meeting resulted in a resolution condemning the US and its allies for their military alliance of transforming into an "invasive nuclear military bloc."

KCNA labelled the US as the "most reactionary" state, asserting its anti-communist policies pose a direct threat to Pyongyang's national security, according to Yonhap.

Kim called for refining warfare tactics to counter "the shifting war attempts by enemies" and ordered continuous enhancements to the army’s warfare capacities.

North Korea also criticised the military cooperation between South Korea, the US and Japan as escalating regional tensions.

Additionally, Pak Thae-song was appointed the new premier during the session, replacing Kim Tok-hun.

The leadership change reflects Kim's efforts to adapt to what he perceives as mounting external threats.