Japanese exports to China in the first half of this year decreased to the lowest level in four years amid strained ties between the top two economies in Asia as well as China's economic slowdown.

Despite the depreciation of the yen against the Chinese yuan, Japan's exports to the Chinese mainland declined 16.7 percent year-on-year to $61.43 billion in the January-June period. In the same period, the United States replaced the Chinese mainland as Japan's biggest export market, the first time in five years, with exports valued at $65.56 billion, according to the Japan External Trade Organization.

"Japan's decreasing exports to China mainly came from weak demand in China, which was caused by deteriorated bilateral ties as well as slower economic growth in China," said Li Xiangyang, director of the Institute of Asia-Pacific Studies under the Chinese Academy of Social Sciences.