It's pretty clear to every world leader now that the only guarantee of security is to have your own nuclear weapons, or to have a solid mutual defense treaty with a nuclear power. President Zelensky has basically stated that if Ukraine doesn't receive sufficient conventional military aid then they'll be forced to pursue nuclear weapons development. Whether they are actually capable of doing this before being conquered by Russia is unknown: they have multiple civilian nuclear power plants and skilled engineers but still it takes a lot to build an operational weapons system including the delivery platform.

https://www.newsweek.com/nato-ukraine-membership-progress-do...

Regardless of what ultimately happens in Ukraine, nuclear proliferation is obviously going to accelerate. This is the very real consequence of the international community failing to collectively oppose Russian aggression.