It's unknown whether the repairs of the aircraft are related to their re-equipment for the use of nuclear warheads.
The annual public procurement plan of the Ministry of Defense of Belarus includes an item on major repairs of Su-25 attack aircraft. In total, it is planned to purchase repair services for eight aircraft from June to December this year.
According to The Military Balance (for 2023), the Belarusian Air Force has at least 22 Su-25 attack aircraft of various modifications in service. Some more aircraft may be in storage. Therefore, the Belarusian Ministry of Defense is going to conduct major repairs of ⅓ of the attack aircraft fleet.
Su-25 are in service with one military unit – the 116th Assault Air Base (military unit 19764), which is stationed at Lida airfield.
Major repairs of aircraft are not unusual. For example, in 2020, it was reported that four Su-25 aircraft were subject to major repairs at the 558th Aircraft Repair Plant in Baranavichy.
We recall that in summer 2022, it was announced that Su-25 attack aircraft of the Belarusian Air Force would be re-equipped to carry nuclear weapons. And in April 2023, it was reported that flight and engineering staff of the Belarusian Air Force had completed training on the program of operation and combat use of Su-25 attack aircraft, including the use of special (nuclear) warheads.
It is unknown whether the scheduled repairs of the attack aircraft are related to their re-equipment for the use of nuclear warheads.