The United States urged North Korea on Sunday to honor commitments and obligations to give up its nuclear program after the North's leader said he will continue to pursue his trademark policy of simultaneously seeking nuclear and economic development.

"We are aware of the comments and continue to call on North Korea to focus on taking concrete steps toward fulfilling its commitments and international obligations," a senior U.S. administration official told Yonhap News Agency on background.

Earlier in the day, the North's leader Kim Jong-un told the Workers' Party Congress that he will "permanently" defend the pursuit of his signature "byeongjin" policy," making clear that he has no intentions to give up nuclear weapons.

Calling the North a "responsible nuclear weapons state," Kim also said the country won't use its nuclear arms first unless its sovereignty is threatened by other countries with nuclear bombs, and will fulfill its nonproliferation obligations and push for global denuclearization.

By "global denuclearization," Kim apparently meant the North won't denuclearize unless everybody else does.

The State Department also urged Pyongyang to carry out its commitments.

"U.N. Security Council resolutions require North Korea to suspend all activities related to its nuclear and ballistic missile programs and to abandon them in a complete, verifiable and irreversible manner," State Department spokesman Ory Abramowicz told Yonhap.

North Korea has conducted four nuclear tests so far: in 2006, 2009, 2013 and January this year. The country has also conducted a series of long-range missile and rocket launches since 1998. In its most recent launches in late 2012 and February this year, the North succeeded in putting a satellite into orbit.

Analysts have warned that it is only a matter of time until the North develops nuclear-tipped missiles. Some experts have recently warned that the communist nation's nuclear arsenal could expand to as many as 100 bombs by 2020.

The six-party talks aimed at resolving the North Korean standoff have been stalled since late 2008. North Korea demands the unconditional resumption of negotiations, while the U.S. says that Pyongyang must first take concrete steps demonstrating its denuclearization commitments. (Yonhap)