The Belarusian defense ministry announced on Monday that they have begun joint air force drills with Russia.

A range of actions are to be carried out until February 1, including reconnaissance and support for ground troops.

Ukraine, neighboring Belarus, has stepped up its guard, saying Russia has been strengthening its aviation grouping in Belarus under the guise of holding the joint exercise. Ukrainian officials say the threat of missile and air attacks from Belarus is increasing.

Ahead of the drills, Russia's new deputy commander, Oleg Salyukov, visited Belarus last week to inspect the joint troops.

The US think-tank, the Institute for the Study of War, revealed on Sunday "the most dangerous course of action of a Russian offensive against northern Ukraine remains unlikely at this time." It calls Russia's moves "anomalous activities that intensify the information operation that Russia will attack Ukraine from Belarus."

The move comes as Russian forces are continuing their attacks in Ukraine. A Russian missile struck a nine-story residential building in the eastern city of Dnipro on Saturday.

The deputy head of Ukraine's presidential office, Kyrylo Tymoshenko, said on social media on Monday that 35 people were killed in the attack, including two children, and 75 others were wounded. 35 people remain unaccounted for.