Ukraine struck Russia’s largest oil refinery, located in the city of Omsk, on Monday, marking what its forces say was its furthest-ever drone attack in the war.
The Omsk facility, which processes about 21 million tons of oil a year, is in Western Siberia and about 1,700 miles from Ukrainian territory — roughly the distance between Los Angeles and Houston.



From what I read a few days ago one of the conditions for US aid under biden was that Ukraine make no strikes on russian soil. When trump pulled all the aid to Ukraine it was a huge blow, but also took the leash off.
After that all they had in their way was developing the actual drones and techniques to make the strikes, as well as planning them.
As far as I know, the condition was that US (nor NATO) weapons can’t be used on attacks to Russian soil. That’s one part why Ukraine has basically done a world record speedrun on native drone production. No one has (nor can) deny them from using their own weapons how they see fit.
Removing stupid limitations on how they can hit back has helped, but that was mostly for short(ish) range missiles.