Russian President Vladimir Putin | (AP Photo/Pavel Golovkin)

Vladimir Putin has threatened to hit new targets if the West supplies longer-range missiles to Ukraine in the fight against Russian invaders.

The warning came hours before the Ministry of Defence announced it would help Ukrainian fighters defend their country by sending rocket launchers that can hit targets 50 miles away.

Explosions rocked Kyiv in the first assault on the capital in weeks as Russian strategic bombers fired missiles from as far away as the Caspian Sea.

Putin said the “fuss” around Western weapon supplies to Ukraine was designed to drag out the conflict, as Russian troops struggle against dug-in defenders in the eastern Donbas region,

He warned that if the US dispatched longer-range missiles to the war zone, “we will strike at those targets which we have not yet been hitting”.

The MoD said it will send the M270 multiple-launch rocket system in “a significant boost in capability for the Ukrainian forces”.

The move was “coordinated closely with the US decision to gift the high mobility artillery rocket system” to Ukraine.

It followed pleas from Ukraine for “longer-range precision weapons in order to defend themselves from Russian heavy artillery used to devastating effect in the eastern Donbas region”, said the MoD.

Defence Secretary Ben Wallace added: “The UK stands with Ukraine in this fight and is taking a leading role in supplying its heroic troops with the vital weapons they need to defend their country from unprovoked invasion.

“If the international community continues its support, I believe Ukraine can win. As Russia’s tactics change, so must our support to Ukraine.

“These highly capable multiple-launch rocket systems will enable our Ukrainian friends to better protect themselves against the brutal use of long-range artillery, which Putin’s forces have used indiscriminately to flatten cities.”

Yesterday’s attacks on Kyiv shook two of the capital’s eastern districts, Darnytskyi and Dniprovskyi, according to Ukraine’s air force and the city’s mayor.

Ukrainian officials said the missiles were launched from nuclear-capable Tu-95 Bear bombers.

One flew “critically low” over a nuclear power plant in the southern Mykolaiv region and was probably destined for Kyiv, said state nuclear power operator Energoatom.

Serhiy Leshchenko, an aide to President Volodomyr Zelenskiy’s chief of staff, said the missile volley targeted railway infrastructure.

Russia’s defence ministry said it had fired rockets from long distance and destroyed T-72 tanks and armoured vehicles supplied to Ukraine by eastern European countries and held in a rail car repair building.

Presidential adviser Mykhailo Podolyak called for more Western sanctions on Russia over the strikes, adding: “ Today’s missile strikes at Kyiv have only one goal – kill as many as possible.”