Russia and Belarus launched joint air force exercises on Monday, in a move that Ukraine sees as a "guise" for yet more airstrikes on the country.
The drills come as Russia's special military operation, now in its 11th month, grinds on with fighting in eastern Ukraine and a campaign of airstrikes on Ukraine's critical infrastructure.
The Belarusian defense ministry said the allies would carry out joint air patrols along the Belarusian border, airborne landings and support operations for ground troops, as well as train for deliveries of supplies and evacuations of wounded soldiers.
"The main purpose of the exercise is to improve interoperability in the joint execution of training and combat tasks," it said.
Pavel Muraveyko, first deputy state secretary of Belarus' Security Council, told the Belta state news agency that the exercises are "exclusively defensive", but warned that Minsk is "ready for any provocative actions from Ukraine".
The Belarusian military said on the Telegram messaging app that it has activated all of its air force and air defense sites for the drills with Russia.
Ukraine has repeatedly warned of possible attacks coming from its northern neighbor Belarus, though some analysts assess the possibility of direct involvement by Minsk as low.
Ukraine's General Staff said the joint aviation drills were a "guise "and that there is a high danger of further Russian air and missile strikes throughout Ukraine.
In a report by the state TASS news agency, an unidentified source in the military said Russia has produced the first set of Poseidon nuclear-capable super torpedoes for use by the Belgorod special-purpose nuclear submarine.
The Poseidon is described as an "intercontinental nuclear-powered nuclear-armed autonomous torpedo "with its own nuclear power supply, the development of which was announced by Russian President Vladimir Putin in 2018. He predicted at the time that it would be a fundamentally new type of nuclear weapon.
In a phone call with Turkish President Recep Tayyip Erdogan on Monday, Putin slammed Kyiv's "destructive" policies and the growing Western arms supplies to Ukraine.
Kyiv was pursuing "a destructive line" and that it had "bet on the intensification of hostilities with the support of Western sponsors, who are ramping up supplies of weapons and military equipment", Kremlin spokesman Dmitry Peskov quoted Putin as saying.
Peskov also responded to a decision by Britain to send Challenger 2 tanks to Ukraine, saying Western supplies of heavily armored vehicles to Ukraine are not likely to change the situation on the battlefield.
On Tuesday, Russia said that its armed forces would undergo "major changes" from 2023 to 2026, including changes in its composition and administrative reforms.
The defense ministry said that the changes would happen as Russia boosts the number of its military personnel to 1.5 million.