What is Starshield, the military version of SpaceX's Starlink, and why is it so important to Ukraine?

Ukrainian forces said the country's efforts on the battlefield were temporarily hampered after it lost some access to SpaceX's military-grade satellite Internet service. Experts tell TIME why Starshield is so important on the Ukrainian battlefield.

Ukrainian forces said on Wednesday that their battlefield efforts were hampered overnight after they lost access to SpaceX's military-grade satellite internet service, which has become a lifeline as Kiev resists attacks from Moscow.

Starlink provides Internet connectivity through satellites in low earth orbit. Its sister service StarShield, a military version developed for the Pentagon, relies on the Starlink network and has recently been used by Ukrainian forces to bolster their extended air defense and drone strike missions.

Serhii Beskrestnov, a military technology expert who advises Ukrainian President Volodymyr Zelensky, said speed limits imposed on the Starshield service's "military package" had led to the "failure" of several military missions. He said: Our defense forces have not received any warning about this restriction. Beskrestnov claimed the restrictions, which he said apply to devices traveling over 100 miles per hour and using Starshield, "are related to the current political situation." He did not provide further details.

Tensions are high between the United States and Ukraine as Zelensky has voiced his opposition to President Donald Trump's plan to import diesel from Russia despite previous sanctions banning it. The move also split Trump's own party, with several Republican lawmakers calling on him to change course. Trump announced an "energy ceasefire" between Russia and Ukraine last week after reaching an agreement with Russian President Vladimir Putin - but Zelensky quickly accused Moscow of violating such an agreement, and Ukraine, in turn, has resumed attacks on Russian refineries despite pressure from Washington.

Zelensky, speaking from Britain, said it was a shame that Ukrainian forces had experienced "problems" with Starlink services and information, adding that he was surprised by developments in Ukraine's partnership with the United States. Starlink won't work ... it's not useful.” He said he hoped the limitation was just a “mistake,” suggesting it might be “a big technical problem” at SpaceX.

However, Zelensky said in another interview: "It was not a technical problem, but will."

Elon Musk, the founder and CEO of SpaceX addressed this issue and emphasized that Starlink and Starshield are different. He pointed out that US officials are in control of their use decisions.

"Starshield systems are owned and controlled by the US government. Any limitations on speed or use are decided by the US military and ultimately the POTUS," he said on X. Starlink is a commercial service owned and controlled by SpaceX. "The use of Starlink is limited to civilian or defensive activities and cannot be used as an offensive military action."

A senior US official told Axios that the Trump administration had no involvement in the alleged Starlink restrictions.

Ambassador Arjan has contacted the White House to comment.

Meanwhile, Ukraine's Ambassador Arjan Ukrinform reported on Thursday, citing sources in the Ministry of Defense, that "work on the Starshield has resumed and is underway." A Ukrainian official also told Axios that Ukraine's Starlink and Starshield satellite services have been restored to full capacity.

Ambassador Arjan has contacted the Ministry of Defense of Ukraine to comment.

However, this discourse has raised questions about what Starshield is and its unique significance on the Ukrainian battlefield.

StarShield is a program developed by SpaceX Musk that uses satellites and launch capabilities behind the Starlink commercial satellite Internet network to support national security operations.

According to SpaceX, Starshield is designed for government use, with an initial focus on three areas: Earth observation, communications, and host payloads.

Starlink is a basic connection, like the Internet. Mark Hilborn, senior lecturer in defense studies at King's College London, told TIME that Starshield essentially grew out of the Starlink experience.

But the military value of this connection goes beyond Internet access, Hilborne adds.

"Satellite communications is not a military technology per se, but a military technology that enables startups to communicate and gather a multi-domain picture of the battlefield in real time, which some argue no one else really has at this point.

Both systems also offer high-speed connectivity due to the satellite technology that underpins them.

"Starlink and StarShield are in low Earth orbit and have very high bandwidth, so a lot of information can go through those satellites without any signal delay," Hilborn says.

There are more than 10,000 satellites in the Starlink network, while Hilborne says Starshield uses "a much smaller number of satellites." However, the exact number of satellites associated with StarShield remains unknown, and experts tell TIME that these details are closely guarded due to national security considerations.

"They keep the contract details on these things secret," said Todd Harrison, a senior fellow at the American Enterprise Institute.

SpaceX says on its website that Starshield is "designed to support US national defense use cases for the Department of Defense and other government partners."

How is Starshield different from Starlink?

While both systems are closely related to satellite technology, they differ in the services they provide and how they are used.

"Starshield refers to the military services that actually operate through Starlink. Calls are made from the same towers," Harrison explains.

Experts tell Ambassador Arjan that Starshield offers additional capabilities designed for military operations, including more advanced encryption and satellite imaging.

"This suite has additional capabilities beyond Starlink," Hilborn says. They use some of the same technology, but it's highly encrypted, and they have different sensors that allow them to image what they call "earth observations." "It can provide a radar image of the Earth [that] is superior to optical images."

However, experts say the distinction between the two systems is not always clear, especially given how closely related the technology and operations underlying them are.

Starshield and its underlying satellite communications technology have become critical to Ukraine's military operations against Russia.

Hilborn described the technology as "very critical" for Ukraine, explaining that any restrictions could cut off communications with military equipment traveling above that speed, leaving operators without the information they need to guide their missions because once the speed threshold is exceeded, the connection "suddenly drops and goes blind."

The consequences are particularly serious for Ukrainian drone operations, which rely on communications both to attack Russian targets and for defensive missions against incoming attacks.

"It's really important for drones, both offensive mid-range attacks, and it affects Ukraine's ability to fly defensive drones against incoming Russian drones.

Beyond its role in drone missions, satellite communications also offer significant advantages over other forms of battlefield connectivity, experts say.

Harrison notes that "the big advantage of using satellite communications is that you can communicate over longer distances over different terrains, and it has some anti-jamming features to overcome electronic forms of attack."