Story highlights The Rev. Jesse Jackson has offered to go to Pyongyang

Ambassador Robert King was scheduled to visit and discuss Bae's case

North Korea has held Bae, a Korean-American, since November 2012

Annual U.S.-South Korean military drills, which anger Pyongyang, begin later this month

North Korea has rescinded its invitation for a U.S. envoy to visit the secretive nation to discuss the fate of Kenneth Bae, a Korean-American man who is being held there, a State Department official said Sunday.

Bae, of Lynwood, Washington, was arrested in November 2012 in Rason, along North Korea's northeastern coast . Pyongyang sentenced him last year to 15 years of hard labor, accusing him of planning to bring down the government through religious activities.

He is widely reported to have been carrying out Christian missionary work in North Korea. Bae, 45, operated a China-based company specializing in tours of North Korea, according to his family, who have described him as a devout Christian.

No reason was given for the trip cancellation. State Department spokeswoman Jen Psaki expressed disappointment that Ambassador Robert King's visit was called off and noted North Korea had said it wouldn't use Bae as a "political bargaining trip." This is the second time North Korea has canceled a planned visit by King.

Bae was moved to a hospital last year after his health deteriorated. But last week the United States said he had been moved back to a labor camp, a development his family described as "devastating."

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"We again call on the DPRK to grant Bae special amnesty and immediate release as a humanitarian gesture so he may reunite with his family and seek medical care," Psaki said Sunday. "We will continue to work actively to secure Mr. Bae's release."

The Rev. Jesse Jackson, the U.S. civil rights leader, has offered, at the request of Bae's family, to "travel to Pyongyang on a humanitarian mission focused on Bae's release," Psaki added.

She said that annual joint military exercises by U.S. and South Korean forces, due to begin later this month, are "in no way linked to Mr. Bae's case."

Tensions over exercises

The large military drills anger the nuclear-armed North Korean regime, which says it views them as a prelude to an invasion. Last year, Pyongyang's threatening rhetoric reached alarming levels during the exercises, heightening tensions in the region.

North Korea has been urging the South not to take part in the drills -- a call that Seoul and Washington have rejected.

This year's exercises, involving thousands of U.S. and South Korean troops, will begin February 24, United States Forces Korea said Monday.

One of the exercises, Key Resolve, in which about 5,200 U.S. troops will participate, will run until March 6. The U.S. military says Key Resolve makes sure forces are prepared to defend South Korea and trains them to "respond to any potential event on the peninsula."

The other exercise, Foal Eagle, in which about 7,500 U.S. troops will take part, continues until April 18. Foal Eagle, according to the U.S. military, is "a series of joint and combined field training exercises" that combine ground, air, naval, expeditionary and special operations.

United States Forces Korea said the North's Korean People's Army had been informed of the dates of the exercises and of "the non-provocative nature of this training."

The dates of the drills overlap with planned reunions of families in North and South Korea who were separated by the Korean War in the 1950s.

The reunions of about 200 people -- 100 from each country -- are scheduled to take place between February 20 and 25 at a resort on the North's side of the heavily militarized border.