SEOUL, Korea, Republic Of -- North Korea's development of banned long-range missiles is in "final stages," the country's leader Kim Jong Un was quoted as saying in his New Year's message.

Kim also threatened to boost his country's military capability unless the U.S. ends war games with rival South Korea, according to Seoul's Yonhap news agency, which monitored Kim's address on Sunday.

Under Kim, who rose to power following his father's death in 2011, North Korea has seen steady progress in its nuclear and missile programs, including two nuclear tests this year. It recently claimed a series of technical breakthroughs in its goal of developing a long-range nuclear missile capable of reaching the continental United States.

UN resolutions call for an end to North Korea's nuclear and missile tests.