Democratic lawmakers are probing SpaceX over Russia’s reported use of Starlink in Ukraine, saying that recent developments raise questions about SpaceX’s “compliance with US sanctions and export controls.”

SpaceX CEO Elon Musk last month denied what he called “false news reports [that] claim that SpaceX is selling Starlink terminals to Russia,” saying that, “to the best of our knowledge, no Starlinks have been sold directly or indirectly to Russia.” But Musk’s statement didn’t satisfy US Reps. Jamie Raskin (D-Md.) and Robert Garcia (D-Calif.), who sent a letter to SpaceX President Gwynne Shotwell yesterday.

“Starlink is an invaluable resource for Ukrainians in their fight against Russia’s brutal and illegitimate invasion. It is alarming that Russia may be obtaining and using your technology to coordinate attacks against Ukrainian troops in illegally occupied regions in Eastern and Southern Ukraine, potentially in violation of US sanctions and export controls,” Raskin and Garcia wrote.

Musk has also stated that “Starlink satellites will not close the link in Russia.” However, the concerns raised by Rankin and Garcia are about whether Russia used the broadband service in Ukraine. Their letter said that Ukraine last month “released intercepted audio communications between Russian soldiers that indicated Russian forces had illegally deployed and activated Starlink terminals in certain Russian-occupied areas in Eastern Ukraine.”