NATO Secretary General Jens Stoltenberg on Tuesday warned again of "severe consequences" if Russia uses nuclear weapons against Ukraine.
"The risk of any nuclear attack against Ukraine, the use of nuclear weapons against Ukraine is low but of course the potential impact, the consequences is so big," Stoltenberg said during a live video speech to the Berlin Foreign Policy Forum 2022.
"So, this is a risk we have to take seriously. And we do so by conveying clearly to Russia that there will be severe consequences for Russia if they use a nuclear weapon in Ukraine," he added.
"We have also reminded Russia that a nuclear war cannot be won and must never be fought," Stoltenberg said.
The NATO chief reiterated that his military alliance is "prepared for all eventualities" when it comes to the Russian war on Ukraine.
Stoltenberg ruled out a NATO nuclear umbrella for Ukraine as deterrence against Russia, pointing out that such a nuclear shield was only for member states.
He stated that NATO's "top priority" is to provide more military support for Ukraine, saying: "We all need to do more."
Stoltenberg added that the latest round of Russian missile attacks on major Ukrainian cities was "the most serious escalation since the start of the war" on Feb. 24.
Stoltenberg also said that NATO will deliver air defence systems to Ukraine in the coming days to help the country defend itself against the drones, including those from Iran, that Russia is using to target critical infrastructure.
Ukraine said attacks by swarms of drones had destroyed almost a third of its power stations over the past week after Russia stepped up its attacks on infrastructure far from the front line after suffering a string of military setbacks at the hands of Ukrainian troops.
Addressing a security conference in Berlin, NATO chief Jens Stoltenberg said the answer to the attacks was for the allies to step up their deliveries of air defence systems.
"The most important thing we can do is deliver on what allies have promised, to step up and deliver even more air defence systems," he said.
"NATO will in the coming days deliver counter-drone systems to counter the specific threat of drones, including those from Iran."
Iranian officials told Reuters that Tehran had promised to supply Russia, whose military efforts in Ukraine are being hampered by Western sanctions, with missiles as well as more drones.
"No nation should support the illegal war of Russia against Ukraine," Stoltenberg said.
