"You cannot forever employ 3,000 to 5,000 people in an organising committee," Bach told BBC Sport ... "You cannot have the athletes being in uncertainty."

Of course, the Olympics were initially scheduled for 2020 -- but due to the COVID-19 pandemic, the International Olympic Committee agreed to postpone to Summer 2021.

It's the first time in modern history the Olympics have been postponed.

But now, IOC President Thomas Bach says there's a limit to how far they can push the event ... explaining that if it's not safe to hold the Games in 2021, they're just gonna call the whole thing off.

"You cannot every year change the entire sports schedule worldwide of all the major federations. You cannot have the athletes being in uncertainty."

"You cannot have so much overlapping with a future Olympic Games, so I have some understanding for this approach by our Japanese partners."

Bach says the IOC is committed to the 2021 Games -- but he's keeping it real ... it's impossible to know for sure if the world will be ready for that kind of a gathering with the coronavirus threat still looming.

"We have to be prepared for different scenarios. There is the clear commitment to having these games in July next year."

"At the same time, looking at the scenarios this may require towards the organisation, with regard to health measures, these maybe need quarantine for the athletes, for part of the athletes, for other participants.