North Korea’s Kim Jong Un has appeared in recent days with a bandage about the size of a few postage stamps on the back of his head, in the latest episode to stoke speculation about the reclusive leader’s health.

The bandage was visible in state media images when Kim appeared at a Korean People’s Army event from July 24 to 27, according to NK News site and the Chosun Ilbo newspaper. There were also images at events in late July in which the bandage was gone and a dark greenish spot was visible, they said, citing a review of North Korean state media.

While the leader’s health is one of the mostly closely guarded secrets in North Korea, it has allowed rare glimpses into the 37-year-old leader’s condition as he tries to revive the economy and battles food shortages. State propaganda for decades has portrayed the supreme leaders as being so people-focused that they risk their own well-being.