The Japanese Olympic Committee has told its Youth Olympic Games athletes not to wear their official tracksuits when out and about in the host city of Nanjing, China, due to fears over potential attacks.
The Second Summer Youth Olympic Games starts in Nanjing on Saturday and runs till Aug. 28.
Relations between China and Japan have become strained by disputes over the sovereignty of the Senkaku Islands, which are under Okinawan jurisdiction but claimed by China, as well as interpretations of the two countries' wartime past. They have further worsened since China's creation of an air defense identification zone over the East China Sea, and Prime Minister Shinzo Abe's controversial visit last December to the war-linked Yasukuni Shrine, which honors Class-A war criminals alongside the nation's war dead.
Beijing consistently reminds its people of the 1937 Nanking Massacre, in which it says Japanese troops killed 300,000 people in the then-national capital.
A postwar Allied tribunal has put the death toll at 142,000, but some conservative Japanese politicians and scholars deny a massacre took place.
JOC Executive Board member Yosuke Fujiwara told reporters that they were taking precautions to ensure their athletes were safe in Nanjing.
"When they are outside, we want them to be aware that it might not be totally safe," Fujiwara said.
"In the Athletes' Village we want them to wear the official Japan tracksuit, but in the city normal clothes are fine."