According to reports, explosions were heard at two Russian air bases – one of which houses bombers with nuclear weapons.
On Monday, a fuel truck exploded at Ryazan’s air base killing three servicemen and injuring six others.
The explosion also caused damage to a plane at the base which houses long-range tankers used for refuelling bombers.
Authorities in Saratov, along the Volga River, said that they are also investigating reports of an explosion at the Engels airbase.
This site is home of the Tu-95 strategic bombers and Tu-160 strategic fighters, which were involved in the launch of strikes against Ukraine and are capable to carry nuclear weapons.
Regional media quoted some residents as saying that they saw light flash from the area.
Roman Busargin, the governor of Saratov region, stated that there was no damage to civilian facilities. However, military sites are still being inspected.
Dmitry Peskov, a Kremlin spokesperson, said that Vladimir Putin was being kept informed of ongoing developments.
Sean Bell, a retired Air Vice-Marshal, said that the cause of the explosions is currently unknown. However it seems unlikely that they were caused by long-distance Ukrainian weapons.
Sky News’ he said, “It could be an accident, or it could have been sabotage.”
New wave attacks
It happened as Russia launched a new wave of missile strikes on Monday against Ukraine.
Officials claimed that two people were killed in Zaporizhzhia. A child was also among the three people who were injured.
People crowded into Kyiv’s underground metro to seek refuge amid fresh strikes against the capital.
Women, men and children tried to stay warm with thick coats and hats in cold temperatures of -5C (23F)
The office of the Ukrainian president Volodymyr Zilenskyy reported that three rocket strikes had struck his hometown of Kryvyi Rh, killing one worker and injuring three others.
One person was killed by S-300 missiles in the Kharkiv region.
It happened when Western countries began to impose a $60 per-barrel price limit as well as a ban on certain types of Russian oil.
Fighting will continue at a’reduced pace for several months’
This was part of new measures to increase pressure on Moscow in the wake of the war.
Russia is the second-largest oil producer in the world. Its economy depends on oil and gas sales. However, there are severe international sanctions against Russia for the conflict in Ukraine.