President Vladimir Putin has said Russia is ready to use nuclear weapons if there is a threat to Russian statehood, sovereignty or independence.
Mr Putin also said he hoped the US would refrain from actions that could trigger a nuclear conflict.
His statement is another blunt warning to the West ahead of a presidential vote this week in which he is all but certain to win another six-year term.
In an interview with Russian state television released early on Wednesday, Mr Putin described US President Joe Biden as a veteran politician who fully understands the possible dangers of escalation, and said he does not think the world is heading to a nuclear war.
At the same time, he said Russia’s nuclear forces are in full readiness and “from the military-technical viewpoint, we’re prepared”.
Mr Putin said Moscow is ready to use nuclear weapons in case of a threat to “the existence of the Russian state, our sovereignty and independence”.
The Russian leader has repeatedly talked about his readiness to use nuclear weapons since launching the invasion of Ukraine in February 2022.
The most recent such threat came in his state-of-the-nation address last month when he warned the West that deepening its involvement in the fighting in Ukraine would risk a nuclear war.
Asked in the interview if he has ever considered using battlefield nuclear weapons in Ukraine, Mr Putin responded that there has been no need for that.
He also voiced confidence that Moscow will achieve its goals in Ukraine and held the door open for talks, emphasising any deal would require firm guarantees from the West.
“It shouldn’t be a break for the enemy to rearm, but a serious talk involving the guarantees of security for the Russian Federation,” he said.
Mr Putin said a recent spike in Ukrainian drone attacks deep inside Russia is part of efforts to derail the country’s three-day presidential election, which starts on Friday and which he is all but certain to win.
Russian authorities reported another major attack by Ukrainian drones early on Wednesday.
The defence ministry said air defences downed 58 drones over six regions. One of the drones hit an oil refinery in the Ryazan region, injuring at least two people and sparking a fire. Another was downed as it was approaching a refinery near St Petersburg.
Ukraine, meanwhile, reported more Russian attacks early on Wednesday.
A Russian strike killed two people and wounded another five in the town of Myrnohrad in the eastern region of Donetsk, about 20 miles from the front line, according to governor Vadym Filashkin.
Local rescuers managed to pull a 13-year-old girl out of the rubble of an apartment building.
A five-storey building in the northern city of Sumy was struck by a drone launched from Russia overnight, killing two people and wounding eight, according to the regional administration.
In Ukrainian President Volodymyr Zelensky’s home town, the death toll from a Russian missile attack the previous night rose to five, Gov. Serhii Lysak said.
He said that 43 people were injured in Kryvyi Rih, including 12 children, the youngest a two-month-old infant.
“Every day our cities and villages suffer similar attacks. Every day Ukraine loses people because of Russian evil,” Mr Zelensky said.