North Korea's Kim Jong Un's send top party-military official to China as 'special envoy'

FILE - In this April 15, 2012 file photo, North Korean leader Kim Jong Un, right, chats with North Korean People's Army senior officers, Vice Marshal and the military's General Staff Chief Ri Yong Ho, left, and Vice Marshal and Vice Chairman of the Central Military Commission Choe Ryong Hae, during a mass military parade in Kim Il Sung Square to celebrate the centenary of the birth of his grandfather, national founder Kim Il Sung in Pyongyang, North Korea. Choe, a "special envoy" for North Korean leader Kim Jong Un left Pyongyang on Wednesday, May 22, 2013, for China, the North's only major political and economic benefactor. State media released few details, but the trip comes at a rocky time in ties between the allies. (AP Photo/Ng Han Guan, File) (The Associated Press)

FILE - In this July 18, 2012 file photo, North Korea's Vice-Marshal Choe Ryong Hae, director of the General Political Bureau of the Korean People's Army, speaks during a meeting at the April 25 House of Culture announcing North Korean leader Kim Jong Un's new title of marshal, in Pyongyang, North Korea. Choe, a "special envoy" for North Korean leader Kim Jong Un left Pyongyang on Wednesday, May 22, 2013, for China, the North's only major political and economic benefactor. State media released few details, but the trip comes at a rocky time in ties between the allies. (AP Photo/Jon Chol Jin, File) (The Associated Press)

PYONGYANG, North Korea – North Korean leader Kim Jong Un dispatched a high-profile official and close confidant to travel to China on Wednesday as a special envoy while Beijing is under pressure to rein in its belligerent neighbor.

Choe Ryong Hae, a top Workers' Party official and a vice marshal tasked with supervising the North Korean army, departed on a chartered Air Koryo flight with a political and military delegation. Chinese Ambassador Liu Hongcai was among dignitaries on the tarmac for his departure.

The trip is the highest-profile visit by a North Korean official to China this year, and it takes place as the new leadership in China shows frustration with North Korea and a greater willingness to work with Washington to harry Pyongyang over its nuclear ambitions.

China is Pyongyang's economic and diplomatic lifeline, providing nearly all of its fuel and most of its trade, and foreign analysts said the trip could be an attempt to win more aid and repair ties.

There are signs of strains in relations between Beijing and Pyongyang over North Korea's nuclear ambitions, which included an underground nuclear test in February. That test was followed by U.N. sanctions and a protracted period of high tensions as North Korea threatened nuclear strikes on Washington and Seoul.

The rhetoric has fallen off in recent weeks, and there have been tentative signs of diplomacy in the region.

In one sign of Beijing's move displeasure with Pyongyang, China's state-run Bank of China said this month it had notified the Foreign Trade Bank of North Korea that its accounts were closed and all financial transactions suspended.

Meanwhile, Chinese fishermen said gunmen in North Korean military uniforms held a crew captive at gunpoint for two weeks before finally releasing the boat this week. The ship's owner said the captain was beaten and the vessel's fuel stolen.

Choe's trip is believed to be the first top-level meeting between North Korean and China since Chinese Politburo member Li Jianguo went to Pyongyang in late November bearing a letter from Xi Jinping, who had just been installed as China's party chief.

North Korea watchers in China said during the tense weeks of March and April that Beijing had explored sending an envoy to Pyongyang but decided against it because North Korea would not guarantee a meeting with Kim.

The visit precedes discussions about a trip by South Korean President Park Geun-hye to China next month.

Choe and his delegation may be ask for more economic aid from Beijing and to explain North Korea's recent military moves, including short-range projectile launches off the east coast, said Lee Ji-sue, a North Korea specialist and professor at Myongji University in Seoul, South Korea.

Leader Kim Jong Un hasn't visited Beijing since he took power from his father, Kim Jong Il, who visited China in August 2011 just months before his death that December.

China is North Korea's top trade partner. According to the most recent figures from Korea Trade-Investment Promotion Agency in Seoul, which collects North Korean trade data, China accounted for 89 percent of North Korea's exports and imports in 2011. The 2012 figure was not available.

The numbers show deepening economic ties between North Korea and China in the last few years as the North's economic exchange with South Korea weakened. In 2005, China accounted for 53 percent of North Korea's annual trade, according to KOTRA.

China and North Korea are jointly developing a pair of special economic zones: Rason on the Korean Peninsula's northern tip and Hwanggumphyong, an island in the Yalu River that marks their border to the southwest. Rason has recently begun to develop thanks to Chinese infrastructure projects, but Hwanggumphyong has languished since ground was broken last year.

Choe is close to Kim Jong Un and is often seen on state television standing next to the leader, along with Jang Song Thaek, the uncle who visited China in August last year.

Choe holds a slew of top posts, including director of the General Political Bureau of the Korean People's Army, member of the Presidium of the powerful Political Bureau of the ruling Workers' Party, vice chairman of the Central Military Commission of the Workers' Party, and member of the Supreme Assembly.

Associated Press writer Kim Kwang Hyon in Pyongyang, and Sam Kim, Youkyung Lee and Hyung-jin Kim in Seoul, South Korea, contributed to this report.