Five hundred miles above Earth, there’s a growing layer of trash. Space debris made up of used rocket bodies and dead satellites hurtles through space, moving at almost 18,000 miles per hour. And the US Space Surveillance Network says the layer is growing: The network is tracking around 40,000 objects larger than a few inches circling Earth today, up from 25,000 in 2019.

When debris collides in low Earth orbit it can endanger astronauts and spacecraft and destroy active satellites, or even create a chain reaction and cascade into a dangerous belt or cloud of congestion known as the Kessler Syndrome. In 2016, NASA declared space debris “the number one threat to spacecraft, satellites, and astronauts.”

The problem has become so serious that in a meeting last week, the US Senate Armed Services Committee discussed space debris alongside Russia, nuclear war, and the postponement of an intercontinental ballistic missile test.

As the war in Ukraine continues, satellites’ safety and their vulnerability to attacks from the ground are becoming topics of national security conversations. And it has become harder to determine whether satellites’ transmissions are failing because Russian actors are jamming communication signals to and from satellites or because debris is in the way. A spokesperson for the US National Reconnaissance Office declined to comment on attacks on commercial satellites.

At the Senate committee hearing, US Space Command’s leader, General James Dickinson, called commercial space systems “an essential component of US critical infrastructure and vital to our national security.” He believes that recent events in Ukraine demonstrate how commercial space operations can supply crucial services, like satellite internet service. US businesses hold the majority of about 5,000 operational satellites in orbit today, and it was Planet Labs and Maxar satellite imagery that allowed the world to see signs of hydraulic warfare in Ukraine and a miles-long convoy making its way to Kyiv.

According to data gathered by the Union of Concerned Scientists, a US nonprofit science advocacy organization, more than 80 percent of nearly 5,000 satellites in orbit today reside in low Earth orbit. SpaceX’s Starlink and other constellation projects plan to launch tens of thousands more satellites in the years ahead, dramatically increasing traffic in low Earth orbit and making it harder to recognize potential collisions.

If these satellites become war targets and are destroyed, the ring of space rubbish will grow much bigger. It can also linger for years: Last November, the International Space Station had to dodge debris created by China’s 2007 anti-satellite weapon (ASAT) test. Less than a week later, Russia shot a ballistic missile from the ground, blasting a Soviet-era Kosmos 1408 satellite into more than 1,500 pieces and proving that the country’s technology doesn’t need to be in orbit to take satellites out. This event created a cloud of debris that is expected to remain in low Earth orbit for years, or even decades, according to Space Command.

Russia’s actions drew widespread condemnation. In the US, Secretary of State Antony Blinken said the event signaled behavior that jeopardizes the long-term sustainability of outer space and could “imperil the exploration and use of outer space by all nations.”

NASA administrator Bill Nelson accused Russia of endangering cosmonauts, as well as the lives of people from other spacefaring nations who were near the International Space Station at the time. In response, a Russian military spokesperson called the US “hypocritical.” The spokesperson reiterated accusations previously made by Russian state news agency RIA Novosti, claiming that the US Air Force’s Boeing X-37B orbital vehicle tests were a precursor to plans to launch orbital vehicles with nuclear warheads strapped to them by 2025.