Borders did not save Afghanistan from NATO sending over a million soliders who got all settled in before carrying out the rest of their orders. Nevertheless, 20 years later, NATO left with their tail between their legs because Afghans just wouldn't stop fighting a guerilla against the occupation.
Borders did not save German Jews from Nazis radicalizing over a million people who got all settled in before carrying ot the rest of their orders. Unfortunately, they had trusted their state's monopoly on violence and without the ability to defend themselves most did not survive.
Borders did not save Ukraine from Russia invading with over a million soldiers who, despite not getting to settle in, occupied a large amount of land and killed tens of thousands. However, those borders do prevent Ukraine sympathizers from retaliating against Russia with their full might, because despite Russia just flat out sending in an army to subjugate random people without justification, that border means they supposedly didn't attack the likes of us.
Without borders, the Russian state is an organization. You can only be part of the organization or not. If you are not part of the organization, it doesn't matter whether you're in Melitopol or New York City, inexcusable violence against one is inexcusable violence against all. So if Russia were to attack, you only have two choices: sign up to be part of the Russian state or be one of their potential targets.
Now, it's a valid choice to let yourself be subjugated and hope they don't kill you to save on integration paperwork. It's a valid choice to put your head in the sand and wait for another Russia to pop up closer to you to subjugate you with nobody to help you. But if you like being a free person, the only option is to defend anyone who comes under attack as you would want them to defend you.
I, personally, live under the aegis of nuclear-powered mutually assured destruction. A foreign state attacking me likely isn't possible without a volley of nuclear weapons laying waste to that state. It seems fair if Ukrainians had the same, though perhaps guerilla or conventional military action would be better from a geopolitical de-escalation standpoint. Either way, anyone who doesn't want to be the victim of genocide would have to treat a Russian invasion of Ukraine as an attack on their neighbor, and retaliate proportionally. The combined might of everyone in Europe and North America and everywhere else that respects human rights would be comparable to that of NATO and would come to the defense of the ones attacked.
So the Russian state and its leadership would likely not survive, and they would know this for a fact when deciding whether to attack anyone. So what would be stopping Russian leadership from committing any acts of violence? Basic self-preservation.
And sure, those soldiers getting a nice beach head might make destroying the Russian state a bit more costly. But that doesn't make Putin any less dead by the end of it.
For context, this is what the street above this station looks like, and what this propaganda piece by Singaporean state media would have you believe means "the only way to improve public transit is to build an expensive underground subway system where everyone who gets off at this station has to go up 43 meters of escalators".
So hooray for another car supremacist boondoggle. It's better than nothing...