Russia is believed to have been mobilising MiG-31 fighter jets and radar stations located close to Ukraine's eastern border, stoking fresh tensions in the region.
According to the National Security and Defence Council of Ukraine, a unit of advanced interceptor jets have been deployed to Millerovo airbase in Russia's Rostov Oblast region, near the Ukrainian border.
"[Russian Federation] continue to concentrate army units at the border, with radar stations and MiG-31 fighter jets," the council wrote in its Twitter account.
It is still unclear how many warplanes have been mobilised.
The Council went on to suggest the latest mobilisation exercise is to take control of the airspace above Luhansk Oblast, a region which is under pro-Russian separatists.
In a press conference earlier this week, the Council's spokesperson Andriy Lysenko told reporters: "We notice the accumulation of Russian troops in the regions bordering with Ukraine. In particular, the airfield Millerovo in the Rostov region relocated its aviation unit, which was based in Perm."
The Aviationist also cited Ukrainian officials as sighting Russian tanks along the frontier.
Moscow has not commented about the Council's accusation.
The National Security and Defence Council of Ukraine's Twitter account is also releasing infographics showing the reported build up of Russian forces and the state of the conflict with Ukraine.