Olympics chief Thomas Bach on Thursday said 2021 was the "last option" for holding the delayed Tokyo Games, stressing that postponement cannot go on forever.
Bach told the BBC that he agreed with Japan's stance that the Games will have to be cancelled if the coronavirus pandemic isn't under control by next year.
In March, the Tokyo 2020 Olympics were postponed to 23 July 2021 as the coronavirus spread across the globe, killing hundreds of thousands of people and making international sport impossible.
"Quite frankly, I have some understanding for (Japan's position) because you cannot forever employ 3 000, or 5 000, people in an organising committee," the International Olympic Committee president said.
"You cannot every year change the entire sports schedule worldwide for all the major federations.
"You cannot have the athletes being in uncertainty, you cannot have so much overlapping with a future Olympic Games."
The Olympics have never been cancelled outside of the world wars, but Japanese officials have been clear that they have no intention of postponing the Games again beyond next year.