North Korean leader Kim Jong Un said Monday a nuclear button is always on his desk and stands ready to be pressed if the country is threatened by the United States, but he struck a surprisingly conciliatory note on relations with South Korea.

In his nationally televised New Year's address, Kim voiced his preparedness to send a North Korean delegation to next month's Winter Olympic Games in Pyeongchang, even as his country becomes increasingly isolated from the international community over its defiant pursuit of nuclear weapons.

While extending an apparent olive branch to South Korea, Kim said the focus this year will be on "mass producing nuclear warheads and ballistic missiles" toward "operational deployment," making North Korea's economy even more independent and improving the standard of living of its people.

Kim warned that the United States will be unable to start a war because of his country's upgraded nuclear capabilities, which have provided a "powerful and reliable" deterrent that is "irreversible with any force."

"The United States can never fight a war against me and our state," he said. "A nuclear button is always on the desk of my office and this is just a reality, not a threat."

He claimed that all parts of the U.S. mainland are already within range of North Korea's nuclear weapons.

(KCNA/Kyodo)

His New Year policy speech, delivered for the sixth straight year, was filled with bellicose remarks against the administration of U.S. President Donald Trump, which has said "all options are on the table" in addressing North Korea's nuclear arms program.

But Kim, wearing a light gray Western-style suit with a tie and glasses, said North Korea is open to talks with South Korea on its possible participation in the Pyeongchang Olympics, which will be held on Feb. 9-25.

It is the first time that North Korea has expressed its willingness to take part in the upcoming winter games.

Kim wished for the success of the event and said the two Koreas should improve relations as 2018 is a "year of significance" for both sides.

For his government, he noted that the 70th anniversary of North Korea's founding in September will be celebrated as a "great auspicious event."

"In order to host the great events...we should melt the frozen north-south relations, thus adorning this meaningful year as a year to be specially recorded in the history," he said.

South Korea's presidential office welcomed Kim's offer to send a delegation to the Pyeongchang Olympics and his intent to restore inter-Korean relations.

Park Soo Hyun, a spokesman for South Korean President Moon Jae In, said the Olympics will contribute to peace on the Korean Peninsula and in the rest of the world if they end in a success.

Still, to that end, he again demanded that South Korea stop conducting joint military exercises with the United States. North Korea has long regarded them as rehearsals for invasion.

In the hope of lowering tensions, South Korea's government wants to secure North Korean athletes' attendance, with President Moon Jae In proposing to the United States to delay annual military drills between the two countries until after the major sports event and the Paralympics to be held on March 9-18.

Kim made no reference to Japan, another major ally of the United States in the region, which has said that now is not the time for resuming dialogue with North Korea but for maximizing pressure on it.

The 30-minute speech, monitored in Beijing, could provide hints as to the North Korean government's behavior in 2018.

In his previous New Year's address, Kim asserted that North Korea had "entered the final stage" of preparing to test-launch an intercontinental ballistic missile.

In line with his statement, North Korea in July last year test-fired for the first time a long-range missile that could potentially deliver a nuclear warhead to the U.S. mainland.

Including that launch, North Korea fired last year three ICBMs, most recently in late November, and more than 15 other ballistic missiles, and detonated its most powerful nuclear weapon to date in September.

The ICBM fired on a steep "lofted" trajectory on Nov. 29 reached an apogee of 4,475 kilometers, a distance regarded as more than sufficient to strike any part of the United States if launched on a standard angle.

Following the third ICBM test, North Korea declared it had "finally realized the great historic cause of completing the state nuclear force," and insisted that the country's weapons program is aimed at defending itself from the United States.

Those tests in 2017 proved North Korea has made significant advances in its nuclear and missile capabilities, despite rounds of tough international sanctions, and escalated fears of conflict.

Trump, who took office in January last year, has not ruled out a military option for dealing with North Korea and his war of words with Pyongyang has further raised tensions.

North Korea will mark the 70th anniversary of its founding on Sept. 9 amid multiple U.N. sanctions, including a cutoff of oil supplies, which are likely to bite its economy more in 2018.

The country needs to organize huge celebrations for the event, as it always does for a historically important day on its calendar.