]“It’s like a solar storm on steroids,” he said of the potential impact.

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Experts say the damage from a nuclear weapon exploding in low-earth orbit could fry any satellites for hundreds of miles and that the resulting radiation could cause cumulative harm to satellites passing through the affected region for months. The electronics on spacecraft also risk failure as a result of nuclear blast irradiation.

Whether or not Russia deploys a nuke, what’s clear is that the US and its two main adversaries, Russia and China, have developed increasingly advanced programs to wage conflict against each other’s assets in orbit, enhancing their capabilities to take out satellites and disrupt communications networks.

Falco said the Defence Department and others have been looking in recent years at whether China or Russia might be developing capabilities or testing of high-altitude nuclear explosions, which can then create powerful high-altitude electromagnetic pulses.

Moscow and Beijing also have made the assessment that the US depends too much on its communications and spying satellites to give it a tactical advantage.

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“China and Russia view the US as overly reliant upon space for military and information superiority,” the US Space Force said in “Competing in Space,” a January report. “Seeking asymmetric advantages in future conflict, both countries are designing, testing and demonstrating counterspace weapons to deny, disrupt or destroy satellites and space services.”

The US is determined not to be left behind. Although there’s no indication that the US is putting nuclear weapons in space — which would be a violation of the 1967 Outer Space Treaty — it’s widely seen as the most advanced in the world when it comes to space.

In September, the US conducted the first launch in a new constellation of satellites known as “Silent Barker” designed to track Chinese or Russian spacecraft that could potentially disable or damage orbiting American systems.

Silent Barker is a response to efforts by China and Russia to develop systems capable of launching into orbit and taking out other satellites. In its annual threat assessment this year, the US Office of the Director of National Intelligence said China has weapons intended to target US and allied satellites, and “counterspace operations will be integral” to operations by its People’s Liberation Army.

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And while much of it is in the future, some is happening already. Russian President Vladimir Putin’s government has floated the prospect of attacking commercial satellite systems that assist its enemies. The US and its allies have already accused Russia of being behind a sweeping cyberattack on Viasat satellite modems across Europe that affected the Ukrainian military’s ability to communicate on the eve of Russia’s invasion of Ukraine in February 2022.

Experts say neither Russia nor China could detonate a nuclear burst in space without affecting their own systems. But they may judge that the US has more to lose.

“If conflict were close to China or Russia and we were operating at longer range, space might be more important to us than it might be to them,” said Eli Niewood, an aerospace engineer with the government-funded research group MITRE. “There’s lots up there that is not hardened.”