the obama administration considers north korea to be the top national security priority for the incoming administration, a view it has conveyed to president-elect donald trump <u+2019>s transition team, according to people familiar with the conversations. president barack obama, in<u+00a0>a policy of <u+201c>strategic patience,<u+201d> refused to engage his administration in high-level negotiations with north korea, waiting for leader kim jong un to show he was committed to abandoning his nuclear arsenal. current and former administration officials now worry that the pace of north korea<u+2019>s nuclear weapons development, particularly its steady march toward the ability to mount a weapon on a ballistic missile, demands a more aggressive strategy. <u+201c>if we just sit back and continue to let [kim jong un] evolve, we<u+2019>re going to have someone with that capability, which is unacceptable,<u+201d> retired adm. michael mullen, former chairman of the joint chiefs of staff for president barack obama, said<u+00a0>on monday. the task of devising a strategy to deter the north koreans is complicated by transitions and turmoil in the countries that would take part, including u.s. ally south korea. china, which has broad influence over north korea, faces domestic economic challenges and is already loath to destabilize its neighbor and risk a refugee crisis on its border. in south korea, pressure is mounting on president park geun-hye to resign amid a corruption scandal. and the u.s. presidential transition could upend relations with both countries. some white house officials believe that if mr. trump follows through on campaign vows to label china a currency manipulator and slaps chinese imports with hefty tariffs, chinese president xi jinping will make it a point to be uncooperative on north korea. mr. trump also threatened during his campaign to dial back u.s. support for regional defense unless allies pay to keep troops there, raising the potential for a diminished u.s. deterrent in south korea and japan. <u+201c>the new administration should send a clear message to north korea and china: [a north korea with nuclear weapons] is a deal breaker,<u+201d> said park in kook, a former south korean ambassador to the united nations. north korea is estimated to have grown its nuclear arsenal to between 20 and 40 bombs in recent years, after conducting five<u+00a0>weapons tests ,<u+00a0>the most recent in september, according to u.s. and chinese officials. pyongyang is developing its program both through the production of plutonium at its yongbyon nuclear facility and through the enrichment of uranium at secret underground sites. the latter are seen as difficult to target with airstrikes. the north korean threat has been compounded by its advancing ballistic-missile program. pyongyang has regularly tested missiles that could eventually hit the mainland u.s., and american intelligence officials believe north korea is close to mastering the technology to miniaturize a nuclear weapon and deploy it on these missiles. north korea<u+2019>s military now appears to be particularly focused on developing a missile re-entry vehicle to carry nuclear payloads, said olli heinonen, who served as the top weapons inspector at the united nations<u+2019> nuclear watchdog, the international atomic energy agency. <u+201c>they<u+2019>ll eventually get there,<u+201d> he said. the options for the next u.s. administration are limited. to gain chinese cooperation in a joint strategy for deterring north korea, u.s. officials say, the trump administration may have to demonstrate that it is trying a diplomatic approach first before escalating the pressure. such an overture could be followed by new steps to increase economic pressure on north korea.<u+00a0>the u.s. likely would seek to further cut off north korean banking relationships. the biggest step,<u+00a0>some u.s. officials believe, would be getting china to agree to cut off north korean coal exports,<u+00a0>one of pyongyang<u+2019>s biggest earners of hard currency. some new steps already have been taken. the u.s. treasury in september sanctioned a chinese communist party member and her family<u+00a0>and companies<u+00a0>for aiding north korea<u+2019>s nuclear program.<u+00a0>this was the first time the u.s. has gone after such a high-level chinese official for helping the north. the difficulty with sanctions is twofold. first, the north koreans already are far more detached from the world economy and therefore less susceptible to pressure than was iran when an international sanctions regime was imposed because of concerns over its nuclear program. second, imposing more effective economic pressure would require participation by china. without cooperation from beijing, <u+201c>i see little reason to think a combination of sanctions and diplomacy will deter north korea,<u+201d> said richard haass, president of the council on foreign relations. <u+201c>i think the (new) administration has a little time,<u+201d> but will need to decide on its preferred strategy, mr. haass added. that strategy could ultimately be military. but there are no easy options on that front. without at least an implicit agreement with china, military steps could trigger a security crisis in the region. u.s. officials aren<u+2019>t lost on the fact that the 1950-53 korean war brought the u.s. into direct military conflict with beijing, which intervened to bolster kim jong un<u+2019>s grandfather, north korea<u+2019>s founder, kim il sung. already,<u+00a0>beijing has pushed back aggressively on u.s. plans to deploy an antimissile shield in northeast asia and is locked in a tense game of military cat and mouse with american allies over chinese claims in the south china sea. president-elect trump could have to confront the north korean problem early in his term. pyongyang often takes provocative action during u.s. political transitions to get attention and see how the americans will respond. north korea tested its second device in the early months of president obama<u+2019>s first term. <u+201c>the north koreans will up the ante,<u+201d> said james steinberg, who oversaw north korea policy during mr. obama<u+2019>s first term as deputy secretary of state. <u+201c>the status quo, the steady as you go, is not sustainable.<u+201d> write to gerald f. seib at jerry.seib@wsj.com , jay solomon at jay.solomon@wsj.com and carol e. lee at carol.lee@wsj.com
barack obama warns donald trump on north korea threat  - wsj
gerald f. seib jay solomon carol e. lee