Why does Russia focus on ‘indivisible security’ in Ukraine standoff?

Vladimir Putin claims the US and its allies have ignored Russia's security demands. Photograph: Yuri Kochetkov/AP

What does ‘indivisible security’ mean and where did it originate?

At its most crude, it means security should be seen as a collective concept so if the actions of one state threaten the security of another, the principle of indivisible security is breached. Therefore no state should strengthen its security at the expense of another.