The video, uploaded to YouTube by the channel ‘Third Phase of the Moon’, shows what looks like three rings similar to smoke drifting below the ISS.
The rings appear to be too high up to be clouds, which has left UFO enthusiasts believing they are portals or wormholes being used by aliens to monitor us.
Conspiracy theorists Blake and Brett Cousins run the YouTube channel which uploaded the footage from the ISS, and Blake says: “We’ve got three strange anomalies drifting downwards just above the Earth’s atmosphere.
“Is this something extraterrestrial?”
Brett adds: “They look almost like smoke rings and they seem to be drifting.
“I’m not sure these are just anomalous clouds – there’s no other ones in the hemisphere.
“If you look at them closely you’re just not sure.
“Are they portals of some sort?”
The video has now been viewed more than 70,000 times, and left many viewers baffled.
One commenter wrote: “They are too high and too fast for clouds.
“I noticed some ‘UFOs’ cause a steamy vapour when they enter our atmosphere.”
Another said: “They don’t want us to know what’s up there in space.”
However, others were not as convinced.
One person simply said: “Clouds you baboons.”
Another agreed, adding: “They are clouds watch at the beginning. The land mass is moving in the same direction and speed”.
While another gave a different explanation: “Maybe it was a meteor entering the atmosphere and caused a sonic boom which caused the rings?”
This is not the first time that mysterious rings in the sky have attracted the attention of UFO hunters.
In April, onlookers in the Russian city of Novosibirsk spotted the odd phenomenon, while in 2016, one was spotted over Disneyland, California.
The numerous sightings have seen alien hunters clamouring to offer their opinions, with prominent UFO blogger Scott C Waring saying that it is a type of extra-terrestrial space craft.
He wrote about the sighting over Disneyland: “Ring UFOs are super rare, but they have been seen.
“This UFO is over Disneyland and causes the family to worry about an alien invasion.”