President Vladimir Putin on Monday ordered new nuclear weapons drills in the face of Western "threats," as a Ukrainian drone attack killed six people and wounded over 30 in Russia's Belgorod border region.
Russia's defence ministry said the exercises would be held in the "near future" and involve the air force, navy and troops stationed near Ukraine.
Putin has upped his nuclear rhetoric, warning in an address to the nation in February there was a "real" risk of nuclear war.
The Kremlin meanwhile said the drills were a response to Western comments on sending troops to Ukraine.
The defence ministry said the drills were aimed at ensuring Russian territorial integrity in the face of "threats by certain Western officials".
"During the exercise, a set of measures will be taken to practise the preparation and use of non-strategic nuclear weapons," it announced in a statement.
Non-strategic nuclear weapons, also known as tactical nuclear weapons, are designed for use on the battlefield and can be delivered via missiles.
Troops from the Southern Military District, which broders Ukraine and includes the occupied Ukrainian territories will take part in the drills, the ministry said.
Western officials have become increasingly alarmed by the Kremlin's nuclear rhetoric.
The announcement came as authorities in the Belgorod region bordering Ukraine reported the deadliest attack in weeks, as Kyiv said Russian strikes left hundreds of thousands without power.
Belgorod governor Vyacheslav Gladkov said two moving vans and a passenger car in the region "came under attack by Ukrainian kamikaze-drones."
"Unfortunately, six people died at the scene from their wounds as a result of the explosion," he said.
He said 35 others were wounded in the attack that took place near the village of Berezyovka -- some 30 kilometres (18 miles) from the Ukraine border.
Local authorities said the vehicles belonged to a meat production facility. Gladkov said two children were among the wounded and that one man was in "serious condition" and undergoing surgery.
He published an image of a bus with blown windows and a damaged roof.
Belgorod has come under an increasing number of fatal Ukrainian drone and missile attacks.
Moscow has been making steady gains in eastern Ukraine and stepped up its aerial attacks and shelling on Ukrainian border regions.
Kyiv said overnight Russian strikes had targeted energy facilities in the northern Sumy region and northeastern Kharkiv region -- both of which have seen increased attacks for weeks.
Thousands of homes were left without power in the aftermath of the strikes, the Ukrainian energy ministry said.
It said 91 villages in Sumy remain without power and that Kharkiv also suffered power cuts.
The interior ministry said Russian shelling had hit school facilities at night in the village of Zolochiv in the north-eastern Kharkiv region, wounding at least one person.
Kyiv also said that the number of people wounded by Russian shelling one day earlier on Ukraine's city-largest city of Kharkiv has risen by two to 16.
