Aerial images shared by the United States have sparked concerns of a potential Russian invasion of Ukraine. In recent weeks evidence has emerged of an estimated 100,000 Russian troops building up on Russia’s western border.
Ukraine says that Moscow is preparing a sea and ground attack from Russian-annexed Crimea and the Donbass region.
Kyiv has been fighting Russian-backed separatists there since 2014.
The Kremlin denies it plans to invade. But the conflict is alarming Eastern European NATO countries like Estonia, which is now mobilizing its own troops.