At least six people were killed and 35 others injured in a Ukrainian drone attack in Russia's Belgorod on Monday as President Vladimir Putin ordered nuclear weapons drills near Ukraine.
The announcement, which Moscwo says was in response to Western "threats" to deploy NATO troops to Ukraine, came as Russian forces said they captured two villages in the war-battered regions of Donetsk and Kharkiv in eastern Ukraine.
Russian officials in the border region of Belgorod, meanwhile, announced that several children were among the dead in the Ukrainian drone attacks.
Putin has upped his nuclear rhetoric since ordering his army into Ukraine in 2022, warning in February there was a "real" risk of nuclear war.
The Defense Ministry gave no date for the drills but said they would involve the air force, navy and troops stationed near Ukraine.
It said they were aimed at ensuring Russian territorial integrity in the face of Western "threats."
The Kremlin specified that the exercises were a response to statements by French President Emmanuel Macron and British officials.
Russia has in recent days hit out at Macron for telling The Economist magazine he was "not ruling anything out" in the West's response to the conflict in Ukraine, including sending troops to the country.
It has also blasted U.K. Foreign Secretary David Cameron for saying Kyiv has the right to strike targets inside Russia.
'Dangerous rhetoric'
"They are talking about the readiness and even the intention of sending armed contingents to Ukraine – that is, in fact, to put NATO soldiers in front of the Russian military," Kremlin spokesman Dmitry Peskov said.
"This is a completely new round of escalating tensions. It is unprecedented and requires special measures," he added.
Peskov singled out "dangerous rhetoric" issued by Macron, who said the question of sending troops to Ukraine would "legitimately" arise if Russia broke through Ukrainian front lines and Kyiv made such a request.
Macron made similar statements in February.
Ukrainian forces have been dependent on Western military aid to battle Russia but NATO has said it will not send troops into Ukraine.
Russia's Defense Ministry said troops from the Southern Military District, which borders Ukraine and includes the occupied Ukrainian territories will take part in the drills.
"During the exercise, a set of measures will be taken to practise the preparation and use of non-strategic nuclear weapons," it said 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.
Deadly Belgorod attack
In Russia's frontier Belgorod region – under attack for months – Gov. Vyacheslav Gladkov said two moving vans and a passenger car "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, adding that 35 others were wounded in the attack near the village of Berezyovka – some 30 kilometers (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 aerial attacks and shelling on border regions.
The Defense Ministry said its units had "liberated the village of Kotlyarivka in the Kharkiv region" and the "village of Soloviove in the Donetsk People's Republic."
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.
Hundreds of thousands of homes were temporarily left without power in the aftermath of the strikes, the Ukrainian Energy Ministry said.
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.