Ukraine has claimed that the Russian army is making arrangements to stage a referendum on independence from Ukraine in Kherson, a Russian-controlled region in southern Ukraine.
"To control the temporarily occupied territories of Southern Ukraine, the enemy is trying to create military-civilian administrations and has begun preparations for a referendum on a quasi-state entity in the Kherson region (the so-called Kherson People's Republic)," the Ukrainian army said in a Facebook post on Thursday
Russian forces took control of Kherson in the "military operation" Moscow launched on Feb. 24, which has been condemned internationally.
The EU, US, and UK, among others, have implemented tough financial sanctions on Russia.
The Ukrainian General Staff added in the post that ships equipped with powerful Kalibr cruise missiles in the Black Sea pose a threat to Ukraine.
The Russian-made missiles were used in the Syrian war with Russia backing forces of the Bashar al-Assad regime. The missiles can travel three times the speed of sound.
The Ukrainian General Staff added that the cruise missile system has been loaded on the Russian Admiral Makarov frigate at the Sevastopol naval base.
"It is expected that the fire on Ukrainian units will intensify in order to ensure the movement of their troops," it said, adding that Russian forces will advance north to the city of Chernihiv.
Russian forces are also trying to seize control of the settlement of Popasna and Rubijna, and the city of Mariupol in the separatist-held Donetsk region.
At least 1,189 civilians have been killed in Ukraine and 1,901 injured, according to estimates by the UN, which cautioned that the true figure is likely far higher.
More than 4 million Ukrainians have also fled to several European countries, with millions more displaced inside the country, according to the UN refugee agency.