WASHINGTON  –  A bipartisan group of US senators has signed a letter demanding an urgent investigation into disruptions to SpaceX’s Starlink internet network in Ukraine. Starlink is a vital tool allowing Kyiv to guide drones to Russian targets and protect its own skies, but on Tuesday night Ukraine said it had unexpectedly restricted how fast drones could fly while maintaining internet connection. In the letter, sent to the US defence department inspector general, the senators express “grave concern” about reports of speed curbs between 12 and 14 October.

Asked whether the US might have had a role in the slowdown, a US official told the BBC “no such request was ever made by the president [Donald Trump]”. The letter, led by Jeanne Shaheen – a Democrat on the Senate’s Foreign Relations Committee – calls for the inspector general to find out whether the restrictions were caused by the US defence department or its contractors. It says “restrictions reportedly degraded Ukraine’s ability to conduct defensive operations against Russian drone and missile attacks on civilian infrastructure”.

Starlink, which is owned by Elon Musk’s SpaceX, restricted speed limits on Tuesday night to 100mph (160km/h), meaning any weapons that travelled faster than that lost connectivity to the network. On Friday, Ukraine’s President Volodymyr Zelensky told a news conference in Brussels that Starlink services were still being restored in his country. “Has the speed been fully restored to what it was before? No. Is the speed being restored now? Yes,” he said. The senators also say they are “deeply concerned” by reports of disruptions or “glitches” affecting intelligence-sharing and threat-warning capabilities relied upon by personnel operating in Ukraine. “We are particularly alarmed by incidents in which U.S. diplomatic, military, and security personnel were unable to reach designated bunkers during Russian air raids,” the statement says.

“Given the potentially deadly consequences, these incidents require immediate investigation,” the senators add.  The letter’s signatories include Republican Senators Thom Tillis, Susan Collins, Lisa Murkowski and John Cornyn, alongside Senators Richard Durbin, Jack Reed, Richard Blumenthal and Christopher Coons from the Democrats.

SpaceX owner Elon Musk has suggested the US government may be behind restrictions.

On Wednesday Musk wrote on X that “Starshield systems are owned and controlled by the US government. Any limits on speed or usage are decided by the US military and ultimately [the US president]”.