Ukraine appears to be using a large Soviet-era missile system to strike inside Russia, according to the UK Ministry of Defence.

Along with drones regularly hitting Moscow , there have been increasing reports of A-5 GAMMON missiles striking Russia, the department noted in an intelligence update on Sunday.

The weapon also called the S-200 surface-to-air missile system, weighs 7.5 tons and is 36 feet long.

Ukraine has retired the weapon from its air defense role and is now instead using it as a ground attack ballistic missile, the department said.

Forbes reported in July that Kyiv might be repurposing the obsolete weapons for ground attacks to replace its diminishing stockpile of Tochka ballistic missiles.

A video showed what appears to be a V-860 or V-880 missile, the munition used in the S-200 system, hitting the ground in Bryansk Oblast in Russia, just north of the border with Ukraine.

It is unclear how many such attacks have occurred, but Russian news agency Tass reported on Saturday that Kyiv tried to strike Crimea with a re-equipped S-200.

Kyiv has not claimed responsibility for the attacks on Russian territory, but several officials have implied support.

An S-200 can hit targets as far away as 190 miles and as high as 130,000 feet in an air-defense role, and this range should be even further in a ground-attack role, Forbes said.

Strikes inside Russian territory are strategically significant as President Vladimir Putin likely invaded Ukraine believing it would have little effect on Russians, the UK defense ministry noted.