NATO Secretary General Jens Stoltenberg says the Western military alliance has agreed to provide Ukraine with equipment to protect itself against chemical, biological, and nuclear threats from Russia.
Speaking at the emergency NATO summit in Brussels on the war in Ukraine, Stoltenberg said the package includes medical support and training for contamination and crisis management.
It comes amid fears that if the Russian campaign gets increasingly bogged down following the failure of the early assault to achieve its objectives, Vladimir Putin may look to escalate the conflict or resort to a spectacular atrocity to shift the balance in Moscow's favour.
The NATO chief said leaders are concerned, "partly because we see the rhetoric and we see that Russia is trying to create some kind of pretext" that it could use "chemical and biological weapons" in Ukraine.
"Any use of chemical weapons will completely change the nature of the conflict" and "will have widespread consequences", he added.
"It will affect the people of Ukraine, but there's also a risk it will have a direct effect on people living in NATO countries."
"Our top military commander General [Tod] Wolters has activated NATO's chemical, biological, radiological and nuclear defence elements," he said of the move to provide Ukraine with material support.
NATO must provide 'even more military assistance'
Stoltenberg told reporters that NATO leaders have agreed the creation of "four new battle groups" in Bulgaria, Hungary, Romania and Slovakia — bringing the total to "eight multinational NATO battle groups now from the Baltic Sea to the Black Sea".
Outlining a reset of long-term NATO deterrence, the secretary general said it would see the deployment of "substantially more forces... at higher alertness", with more fighter jets, missile defence systems, submarines and combat ships.
The reset also includes plans enhancing cyber defence capabilities.
NATO leaders also agreed that it is of "vital importance" that they provide "even more military assistance" to Ukraine including in cyber security, Stoltenberg said.
He said the "significant military supplies" provided by NATO so far to Ukraine, including anti-tank weaponry, are "proving highly effective."
But he said leaders wanted to avoid further escalation in the conflict "because this could be even more dangerous and even more devastating".
Speaking before the meeting, Stoltenberg spelt out the importance of providing Ukraine with more support, which he said was needed "to be able to respond and address any threat, any challenge to our security, and what kind of decisions they may make in Moscow".
"President Putin has made a big mistake, and that is to launch a war to wage war against an independent, sovereign nation. He has underestimated the strength of the Ukrainian people, the bravery of the Ukrainian people and the armed forces, and therefore they are also meeting much more resistance than they expected," the NATO chief said.
Zelenskyy demands 1% of all NATO arms
Ukrainian President Volodymyr Zelenskyy called on NATO leaders to give one percent of their weapons to Ukraine as they gathered in Brussels one month on the day since Russia launched its invasion.
Speaking ahead of NATO's emergency meeting, he demanded that this cover aircraft, tanks, a rocket system, anti-ship weapons, and air defence equipment, adding that "Russia is using its entire arsenal against us".
"Ukraine does not have powerful anti-missile weapons. It has much smaller aircraft than Russia. Therefore, their advantage in the sky is the use of weapons of mass destruction. And you see the consequences today: how many people were killed, how many peaceful cities were destroyed."
"You have thousands of fighter jets! But we haven't been given one yet. We appealed for tanks so that we could unblock our cities that are now dying," he went on.
"You have at least 20,000 tanks! Ukraine asked for a percentage, one percent of all of your tanks! Give or sell to us. but we do not have a clear answer yet.
"The worst thing during the war is not having clear answers to requests for help," he stressed.
"After such a war against Russia, I ask, never again, never tell us that our army does not meet NATO standards. We have shown what our standards are capable of and how much we can contribute to overall security in Europe and the world, how much we can do to protect against aggression against everything we value, that you value," he added.