Russia said on Wednesday that Ukraine had struck a military airfield on the Azov Sea with six ATACMS ballistic missiles, a move that could prompt Moscow to launch another experimental intermediate-range hypersonic missile at Ukraine.

Russia’s defence ministry said on Wednesday that the “attack by Western long-range weapons will not go unanswered and appropriate measures will be taken”.

It is unclear exactly how Russia will respond.

“I would like to recall the absolutely unambiguous and direct statement of the defence ministry of the Russian Federation made yesterday, where it was clearly stated that a response would follow,” Kremlin spokesman Dmitry Peskov said.

“The response will follow in a manner deemed appropriate. But it will definitely follow,” Peskov said.

Russia fired a new intermediate-range hypersonic ballistic missile known as Oreshnik, or Hazel Tree, at Ukraine on Nov 21 in what President Vladimir Putin said was a direct response to strikes on Russia by Ukrainian forces with US and British missiles.

A US official said on Wednesday that Russia could launch another hypersonic ballistic missile against Ukraine in the coming days, but Washington does not consider the Oreshnik weapon a game-changer in the war.