NATO Secretary General Jens Stoltenberg on Wednesday said the risk of Russia using nuclear weapons amid its war with Ukraine was small, but the Kremlin's "nuclear rhetoric" was irresponsible and dangerous.

"The risk of using nuclear weapons is small, but the Russian nuclear rhetoric is completely irresponsible and dangerous. Russia should know that it is impossible to win a nuclear war and, therefore, it is impossible to produce it," Stoltenberg said. 

He noted that NATO continued to “closely monitor” Moscow's actions, adding “at the moment, there are no changes in the Russian nuclear forces”. 

Russia invaded Ukraine last year, with hostilities still in progress.