SEOUL, South Korea ó North Koreaís surprise call on Monday for direct talks with South Korea could drive a wedge into the decadesold alliance between Seoul and Washington, potentially creating a reprieve from months of tensions but also undercutting President Donald Trumpís tough approach to the nuclear-armed North.A New Yearís Day speech by Kim Jong Un, the North Korean leader, contained a dramatic shift in tone and policy regarding the South. After ignoring South Korea for years, Kim called for urgent dialogue to discuss improving ties and easing military tensions on the divided Korean peninsula, even as he claimed an ability to strike the mainland United States with nuclear missiles.Kim also agreed to a request by President Moon Jae In of South Korea to send a North Korean delegation to the Winter Olympics to be held in South Korea next month.Kimís about-face, which was broadcast on state-run television, came just days after Washington rallied its allies and rivals to support increasingly punishing United Nations sanctions against North Korea.Analysts said Kim was looking for opportunities to weaken international resolve to enforce the penalties, as well as to sow discord between the United States and South Korea.In his customary annual address, Kim said that his country had achieved the historic feat of "completing" its nuclear forces and added that he has a nuclear button on his desk. "The U.S. should know that the button for nuclear weapons is on my table," he said. "The entire area of the U.S. mainland is within our nuclear strike range. Ö The United States can never start a war against me and our country," Kim said.Moon has repeatedly called for dialogue with the North, hoping that talks would ease tensions and lead to broader international negotiations to end its nuclear weapons program.Hours after Kimís speech, Moonís office welcomed the Northís proposal."We have already expressed our willingness to engage in a dialogue with North Korea at any time, in any place and in any format, as long as both sides can discuss restoring their relations and peace on the Korean peninsula," said Park Soo Hyun, Moonís spokesman.Trump, on the other hand, has stressed maximum pressure and sanctions, and even suggested possible military action to force the North to give up its nuclear arsenal.Moon officially supports the enforcement of U.N. sanctions. In recent weeks, his government has seized two oil tankers on the suspicion that they were used in violation of the sanctions to smuggle refined petroleum products into North Korea through ship-to-ship transfers on the high seas.But the South Korean president also agrees with China and Russia that talks are needed to resolve the nuclear crisis. Kimís sudden peace overture Monday will probably encourage both South Korea and China to raise their voices for dialogue."Kim Jong Un is using the Pyeongchang Olympics as a way to weaken the sanctions," said Kim Yong Hyun, a professor of North Korean studies at Dongguk University in Seoul. "He is seeking to create a fissure between Seoul and Washington and between Washington and Beijing."On Nov. 29, when North Korea launched an intercontinental ballistic missile with engines powerful enough to send a warhead to the East Coast of the United States, North Korea already claimed to have completed its nuclear arsenal.Analysts have said that the North has yet to master the missile technology needed to protect a nuclear warhead when it re-enters the Earthís atmosphere from space. They said that despite the Northís claim to have completed its weapons program, the regime was likely to conduct more weapons tests to improve its capabilities.But in addition to improving its weapons technology, the North also wants to ease crippling sanctions that limit fuel supplies and hard currency entering the country."After getting nowhere with the Americans, North Korea is now trying to start talks with South Korea first and then use that as a channel to start dialogue with the United States," said Yang Moo Jin, a professor at the University of North Korean Studies in Seoul.The isolated North made major strides last year in its nuclear weapons program. On Sept. 3, it detonated what it called a hydrogen bomb in its sixth and most powerful nuclear test. It has also launched three intercontinental ballistic missiles in the past year.But the country has also faced harsh sanctions from the U.N. Security Council. The council has sought to squeeze North Koreaís main sources of foreign currency by banning its exports of coal, iron ore and sea products and curtailing the employment of North Koreans in other countries. It has also demanded that member nations drastically reduce exports of refined oil to North Korea.For Moon, the inter-Korean talks would provide a badly needed respite after a year in which Kim and Trump regularly exchanged threats of war. Trump has said he could unleash "fire and fury" and "totally destroy North Korea," while North Korea has suggested it could conduct a hydrogen bomb test over the Pacific.Increasingly anxious over a possible armed conflict, Moon seeks to create a lull in the nuclear standoff during the Olympics and use its momentum to start talks with North Korea. Such talks, he hopes, might eventually lead to broader negotiations in which the United States, China and other regional stakeholders could offer economic and diplomatic incentives to the North in return for the freeze and eventual dismantling of its nuclear weapons program.