Ukraine will use US-supplied rocket systems to strike into Russian territory should it deem such attacks necessary, Ukrainian Presidential Adviser Alexey Arestovich said on Thursday. 

Responding to a question about whether the restrictions on the use of US-supplied rocket systems apply to Crimea, a peninsula that overwhelmingly voted to become part of Russia in a referendum, Arestovich said that it belonged to Ukraine. 

“Crimea is ours. It belongs to Ukraine. And they [Russia] know it. Therefore, it will fly to Crimea double-time, should the need arise”, he pointed out, alleging that Kiev has already successfully struck targets on the peninsula.

Arestovich’s comment comes despite US Secretary of State Antony Blinken saying on Wednesday that Kiev has given Washington “assurances” that it won’t use American rockets to attack targets in Russia. 

The Biden administration announced on Wednesday that it would send Ukraine $700 million in new military aid, including the M142 High Mobility Artillery Rocket System, more commonly referred to as HIMARS. This weapon fires barrage rockets with an effective range of around 30km, but can also deploy tactical ballistic missiles that increase the range to up to 300km. Russia has previously raised concerns over such a move, but they were dismissed by Washington.

Arestovich’s statement echoes the claim made by another Ukrainian politician. Egor Chernev, a Ukrainian MP, said on Wednesday that Russian aircraft and military stationed on Russia’s territory are “legitimate targets.” “We have taken on certain obligations, but no one can guarantee where the missile will strike. Kiev has its own weapons, such as howitzers, self-propelled guns, Tactical Operational Missile Complexes ‘Tochka’ which can reach such targets,” he told local news. 

Russia considers Crimea to be an integral part of its territory after the peninsula overwhelmingly voted to part ways with Ukraine and join Russia in a 2014 referendum.

Russia attacked the neighboring state in late February, following Ukraine’s failure to implement the terms of the Minsk agreements, first signed in 2014, and Moscow’s eventual recognition of the Donbass republics of Donetsk and Lugansk. The German- and French-brokered protocols were designed to give the breakaway regions special status within the Ukrainian state.

The Kremlin has since demanded that Ukraine officially declare itself a neutral country that will never join the US-led NATO military bloc. Kiev insists the Russian offensive was completely unprovoked and has denied claims it was planning to retake the two republics by force.