This morning, Russia destroyed one of its own satellites with a ground-based missile, creating thousands of pieces of debris that have spread out into Earth orbit, according to the US State Department. The US has identified more than 1,500 trackable pieces of debris from the event, and many thousands of smaller ones that cannot be traced, Ned Price, a spokesperson for the State Department, said during a briefing.

The news comes amid reports from Russia’s space agency Roscosmos that the astronauts living on board the International Space Station had to shelter in place this morning due to a cloud of space debris that seems to be passing by the station every 90 minutes, the time it takes for the ISS to orbit the Earth.

At first, it was unclear if the debris threatening the space station came from Russia’s anti-satellite, or ASAT, test. The State Department simply indicated that the debris field is a danger to the space station. “This test will significantly increase the risk to astronauts and cosmonauts on the International Space Station, as well as to other human spaceflight activities,” Price told reporters. “Russia’s dangerous and irresponsible behavior jeopardizes the long term sustainability of our space and clearly demonstrates that Russia’s claims of opposing the weaponization of space are disingenuous and hypocritical.”

But at the end of the day, NASA administrator Bill Nelson finally confirmed that the Russian ASAT did indeed cause the astronauts to shelter in place. “I’m outraged by this irresponsible and destabilizing action,” Nelson said in a statement to The Verge. “With its long and storied history in human spaceflight, it is unthinkable that Russia would endanger not only the American and international partner astronauts on the ISS, but also their own cosmonauts.” There are seven people currently living on the ISS, two of which are Russian cosmonauts.

US Space Command, which oversees the tracking of space objects and debris in orbit around Earth, told The Verge in a statement that it was “aware of a debris-generating event” in space this morning.

“We are 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,” US Space Command said in a statement. “We are also in the process of working with the interagency, including the State Department and NASA, concerning these reports and will provide an update in the near future.”

US Space Command has been tracking ASAT tests from Russia over the last couple of years. In 2020, US Space Command reported two tests of Russia’s ASAT technology, known as Nudol. However, both tests did not seem to actually destroy any targets in space.

Private space tracking company LeoLabs confirmed on Twitter that it had observed multiple objects that are now in the location of an old Russian satellite called Kosmos 1408, which has now been confirmed to be the target of the ASAT test.

Mission controllers in NASA’s Johnson Space Center in Houston discussed the cloud of debris passing by the astronauts on NASA’s live feed recording from the International Space Station this morning. “We are a minute and a half from the next debris field transit at this point,” a mission controller said to the astronauts during one pass, according to audio from the live feed recorded by Space.com. “This is going to be a four-minute transit.”

During the first few debris passes this morning, NASA astronauts sheltered inside the SpaceX Crew Dragon currently docked with the ISS, which just brought four new astronauts to the space station last week. Mission controllers directed the crew to close the hatches to various modules on the ISS before sheltering. However, the astronauts eventually opened the hatch to their vehicle and entered the ISS, according to the live feed audio. Later this morning, Roscosmos stated that “the crew is routinely performing operations according to the flight program,” after sheltering this morning. The hatches between the Russian and US segments of the space station are currently open.

“Thanks for a crazy but well-coordinated day,” NASA astronaut Mark Vande Hei said over the ISS live feed to mission controllers. “We really appreciate all the situational awareness you gave us, and it was certainly a great way to bond as a crew starting off with our very first work day in space.” NASA says it will continue to monitor the debris and make sure the crew on the ISS remains safe.

Jonathan McDowell, an astrophysicist at Harvard and satellite tracker, calculated the time of the first debris field pass, which occurred around 2:06AM ET this morning. He found that the passes have occurred roughly every 93 minutes since that first pass. After figuring out the orbit of Kosmos 1408, he found that the paths of the satellite and the ISS do come close to each other every hour and a half.

“What I showed was that the orbital plane of this satellite actually is right through the part of the ISS orbit where they’re getting these warnings,” McDowell tells The Verge.

ASAT tests are often considered political moves that showcase a nation’s capability of taking out satellites. But they are a source of concern for those in the space industry, because of their propensity to cause giant fields of satellite fragments. These fields of debris can span many miles, jumping into higher and lower altitudes. The resulting debris pieces often vary wildly in size, and they can sometimes stay in orbit for years, threatening functioning satellites. Objects in low Earth orbit are moving at roughly 17,500 miles per hour, so if a fragment of space debris collides with another fast-moving satellite, it can cause significant damage or even create more fragments that then threaten other satellites.

China famously conducted an ASAT test in 2007, using a kinetic missile to destroy its Fengyun 1C satellite. The event created thousands of pieces of debris, some of which are still circulating above Earth. In fact, the International Space Station had to boost its orbit last week to avoid one of the fragments from the satellite still in orbit. In 2019, India also conducted its own ASAT test, known as Mission Shakti, creating hundreds of debris pieces after taking out a decaying satellite.

The United States also conducted an ASAT test in 2008, known as Operation Burnt Frost. The US military destroyed a satellite launched by the National Reconnaissance Office that was falling out of orbit. The satellite’s fuel tank contained more than 1,000 pounds of a toxic fuel called hydrazine, and the ASAT test was considered a way to protect people on the ground while exercising anti-satellite technology.

The US State Department is strongly condemning today’s ASAT test by Russia, with Price calling it “dangerous, reckless, and irresponsible” in today’s press briefing. The Department of Defense shares the same concerns, according to John Kirby, the Pentagon’s press secretary. In a separate press conference this afternoon, Kirby noted that Russia did not warn the US that it was about to do the test.

Price of the State Department did not say exactly what the US’s response would be. “[We] don’t telegraph specific measures, but as I said before, we will work with our allies and partners in different ways to make clear that the United States — that the international community — is not going to tolerate this kind of irresponsible behavior,” he said during the State Department briefing.

Update November 15th, 6:30PM ET: This story was updated to include a statement and information from NASA.