According to the US Space Force Ukraine may not be able to use GPS because there are jammers around that prevent them from receiving any usable signal.
General David Thompson, the Space Force's vice chief of space operations, told NBC Nightly News the Russians understand the value and importance of GPS and try to prevent others from using it.
Russia has not directly attacked any satellites in orbit, but the Space Force is keeping an eye out for such possibilities.
Specifically, Russia is targeting the Navstar system of satellites used by the United States and made available openly to many countries around the world, Thompson said.
Russia has its own independent system, called GLONASS, while the Europeans have one called Galileo and China has one called Beidou.
Navstar uses 24 main satellites that each orbit the Earth every 12 hours. The system works by sending synchronised signals to users on Earth. Because the satellites move in different directions, the user receives their signals at slightly different times. When four satellites are available, GPS receivers can use their signals to calculate the user's position, often to within just a few feet.