A space junk threat forced the crew of the International Space Station to take shelter

• A space debris threat forced the 7-member crew of the International Space Station to take cover.
• It is unclear what caused the sudden appearance of the potentially dangerous debris.

The crew of the International Space Station (ISS) was forced to take shelter in their evacuation spacecrafts early Monday morning in response to a threat posed by the sudden appearance of potentially dangerous debris.

US astronauts Raja Chari, Thomas Marshburn, and Kayla Barron and Germany's Matthias Maurer took shelter in the Crew Dragon spacecraft, while Russian cosmonauts Anton Shkaplerov, Pyotr Dubrov and US astronaut Mark Vande Hei sheltered inside a Soyuz craft, Russian state-media reported.

The incident was acknowledged by Russia's Roscosmos State Corporation for Space Activities in a social media post, which said the space station has moved away from the object.

As Insider's Morgan McFall-Johnsen previously reported, there are tens of millions of pieces of space debris orbiting the planet, and when objects collide, they tend to create even more debris, exploding away from the collision site at speeds sometimes as much as ten times the speed of a bullet.

Not only could these pieces damage the systems, but they could also injure or kill astronauts.

The exact nature of the debris and what caused it are unclear, though the US is concerned about a Russian anti-satellite weapons test over the weekend, two US officials told CNN.

In a public statement on the debris, US Space Command said simply that it "is aware of a debris-generating event in outer space."

The command added only that it "is actively working to characterize the debris field and will continue to ensure all space-faring nations have the information necessary to maneuver satellites if impacted."

Insider reached out to the Department of Defense for further comment but has not yet received a response.

Anti-satellite weapons testing generates debris with the destruction of a satellite, and it can linger for a long time. Just last week, for instance, The New York Times reported that the ISS had to maneuver to avoid a piece of space junk generated by a 2007 anti-satellite weapon test conducted by China.