When Chinese President Xi Jinping presided over a massive military parade on a rostrum overlooking Beijing's iconic Tiananmen Square, South Korean President Park Geun-hye sat two seats to the right of Xi.
  
The presence of Park at the rostrum was notable, partly because of her yellow jacket, but also because Choe Ryong-hae, a key aide to North Korean leader Kim Jong-un who also attended the military parade, was barely visible. Choe was seen at the end of a row of other foreign officials watching the event.
  
It was a snapshot of warmer ties between South Korea and China, former battlefield foes as China fought alongside North Korea in the 1950-53 Korean War, and a political chill between China and its only treaty ally, North Korea.

Once dubbed as "forged in blood," the alliance between North Korea and China has been wearing thin as China's Communist Party opened up in the 1970s and Beijing is seeking to defend its interests as the world's second-largest economy.
  
Political ties markedly strained when North Korea conducted its third nuclear test in early 2013, months after Xi officially took power, despite China's message of restraint.
  
The North's young leader also executed his uncle, Jang Song-thaek, who played an influential role in doing business with China, later that year.
  
Zhang Liangui, a professor of Korean studies at the Party School of the Central Committee of the Chinese Communist Party, said the political relationship between North Korea and China is unlikely to improve unless the North changes course on its nuclear ambitions.
  
Zhang expected Choe to make efforts to meet with Chinese leaders during his visit to Beijing.
  
"I think that it may be difficult for Choe to meet with Chinese leaders unless he gives a meaningful answer to the Chinese side, which demands the denuclearization of the Korean Peninsula through dialogue," Zhang said.
  
Despite strained political ties, China is North Korea's economic lifeline and diplomatic backer at the United Nations.
  
South Korea and the U.S. have called for China to do more to rein in North Korea's nuclear and missile programs, but Beijing's stance over its ideological ally, Pyongyang, has often been self-contradictory.
  
Many analysts believe that the Chinese Communist Party leadership won't put enough pressure on North Korea to give up its nuclear ambitions because a sudden collapse of the North's regime could threaten China's own security interests.
  
Kim has never visited China since taking power in late 2011, following the sudden death of his father, Kim Jong-il.
  
Shi Yinhong, a professor of international relations at Renmin University of China, said that the likelihood of Kim visiting China in the near term is low.
  
"After executing Jang Song-thaek in 2013, Kim has shown an unfriendly attitude toward China and China opposes his development of nuclear weapons," Shi said. "It's still no closer to improving the bilateral relations." (Yonhap)