The Russian Defense Ministry warned Romania and other countries against allowing Ukrainian military aircraft to use their airfields, saying that doing so could be regarded as "the involvement of these states in an armed conflict," according to TASS.
"At the same time, we are reliably aware of Ukrainian combat aircraft that previously flew to Romania and other border countries.
Western officials have rejected the requests, saying that such a move would mean entering a direct military conflict with Russia.
Russia is concentrating on creating a land corridor between Luhansk and Donetsk and Crimea, and depriving Ukrainian access to the Sea of Azov and Black Sea, the Ukrainian military claimed in a statement.
Despite these losses, Russia has continued to encircle key Ukrainian cities with air support, the Ukrainian military said on Sunday.
The Russian military in turn claimed that it had shot down several Ukrainian aircraft and destroyed air defense infrastructure.
Russia claims to have shot down 90 Ukrainian aircraft and 59 drones since the fighting began. »