SEOUL, South Korea (AP) -- North Korea has withdrawn its invitation to a U.S. envoy to visit the country over a detained American because Washington perpetrated a "grave provocation" by allegedly mobilizing nuclear-capable bombers during recent military drills with Seoul.
Analysts said the moves signal that possible informal negotiations between the two countries over the release of Kenneth Bae were not going smoothly, with Pyongyang likely seeking some concessions from Washington in return for freeing him.
Bob King, the U.S. special envoy for North Korean human rights, had been scheduled to travel to Pyongyang on Friday for talks on Bae, a 45-year-old tour operator and Christian missionary who has been detained since November for committing "hostile acts." He was sentenced in April to 15 years of hard labor.
An unidentified North Korean Foreign Ministry spokesman said in remarks carried by state media late Saturday that his country intended to allow King's visit even though the U.S. and South Korea were conducting annual military drills.
But he said the U.S. "beclouded the hard-won atmosphere of humanitarian dialogue in a moment" by allegedly infiltrating B-52H strategic bombers into the sky above the peninsula during the exercises. He called it "the most blatant nuclear blackmail against us."
The North Korean statement "may be the result of the fact that compromises are not being struck smoothly in U.S.-North Korea negotiations" over what North Korea wants for releasing Bae, said Lim Eul Chul, a professor at South Korea's Kyungnam University, adding that could include such things as the shipment of aid or the start of formal talks on improving ties.
North Korea appears to be trying to gain leverage on the U.S. by delaying King's trip, but it should eventually allow the trip for talks on Bae because it needs improved ties with the outside world to revive its economy, Lim said.
Analysts say North Korea has previously used detained Americans as bargaining chips in its standoff with the U.S. over its nuclear and missile programs.
International disarmament talks on ending North Korea's nuclear ambitions remain stalled since 2009 and efforts by Washington to negotiate a freeze in the North's nuclear program in exchange for food aid collapsed 18 months ago.
King's planned trip raised prospects for improved relations between the wartime foes as it would have been the first public trip by a U.S. administration official to the country in more than two years.
The annual Ulchi Freedom Guardian drills, which ended Friday, were computer-simulated war games that U.S. and South Korea say are defensive in nature, but which North Korea calls a rehearsal for an invasion. The U.S. military command in Seoul did not immediately comment on the North Korean statement.
Earlier this year, the U.S. took the unusual step of sending nuclear-capable B-52 and B-2 bombers to participate in springtime military drills with South Korea as tension was running high after a string of warlike rhetoric from North Korea, including vows to launch nuclear war. The flights drew a furious response from Pyongyang. Animosities have since eased, with Pyongyang moderating its rhetoric and seeking diplomacy with Seoul and Washington.
State Department spokeswoman Marie Harf said Friday the U.S. was "surprised and disappointed by North Korea's decision" and remains gravely concerned about Bae's health. Bae's family expressed disappointment but said they were holding on to faith that North Korean and U.S. diplomats would resume talks soon. Bae suffers from multiple health problems.
Bae is at least the sixth American detained in North Korea since 2009. The others were eventually allowed to leave without serving their terms, with some releases coming after prominent Americans, including former Presidents Bill Clinton and Jimmy Carter, visited North Korea.
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