Russian and Ukrainian forces are intensifying their attacks against each other in border areas between the two countries.

Russia's defense ministry announced on Tuesday that the country's air defense systems intercepted a Ukrainian drone and a missile over the western Russian region of Belgorod.

Ukrainians are apparently stepping up what are believed to be cross-border attacks against Russia. The governor of the Belgorod region said 25 people had been killed in a Ukrainian attack on December 30.

Kremlin spokesperson Dmitry Peskov said on Tuesday that the Russian military will do everything possible to reduce and then eliminate the threat of Ukrainian shelling attacks on Russian cities.

Meanwhile, Russian forces continue their intensive attacks on the eastern Ukrainian region of Kharkiv, which borders Russia's Belgorod region.

The Kharkiv city mayor said on Wednesday that Russian forces had shelled a children's recreation camp on the outskirts of the city during the night and several buildings were damaged.

The US think tank, the Institute for the Study of War, said in its assessment on Tuesday that Russian sources are reviving longstanding calls for a large-scale Russian offensive operation in the Kharkiv region to create a "buffer zone" with the Belgorod region.