With all eyes on the situation unfolding at the Ukraine border - as separatists in Donbas reporting intensified shelling amid a "general mobilization" of military-age males - Germany's left-leaning Spiegel asks a question fundamental to the entire conflict...
"Vladimir Putin insists that the West cheated Russia by expanding NATO eastward following the end of the Cold War. Is there anything to his claims? The short answer: It's complicated."
The essence of the argument is this; In September 1993, Russian President Boris Yeltsin penned a long letter to US President Bill Clinton, which railed against the eastward expansion of NATO at a time when Poland, Hungary and the Czech Republic were interested in joining the organization. Yeltsin argued that the Russian public saw this "as a sort of neo-isolation" of Russia, and that the "Two Plus Four Treaty" linked to Germany's 1990 reunification "precludes the option of expanding the NATO zone into the East."
As Spiegel writes, "There is essentially no other historical issue that has poisoned relations between Moscow and the West as much in the last three decades as the disagreement over what, precisely, was agreed to in 1990."
Since the 1990 letter, NATO has accepted 14 countries in Eastern and Southeastern Europe, which the Kremlin has complained of haaving been duped every step of the way."
According to current Russian President Vladimir Putin, "You cheated us shamelessly."
"You promised us in the 1990s that (NATO) would not move an inch to the East," he said late last month in comments used to justify his current demands for written guarantees that Ukraine will never be accepted into the Western alliance.
Ukraine, meanwhile, wants to know how fast they can join.
Post-1990 NATO expansion isn't black-and-white though, according to Spiegel - and is muddied by a chorus of 'he-said-she-said' between prominent officials from the early 1990s.
Poland, Hungary and the Czech Republic were admitted into NATO in 1999, right before launching an air war against Yugoslavia which put NATO forces along the Russian border for the first time.
In 2004, the former Soviet republics of Latvia, Lithuania and Estonia joined the Organization, putting NATO even closer to Russian assets.
Now, Russia is demanding that NATO publicly renounce expansion into the former Soviet Republics of Georgia and Ukraine, and recall US forces to the 1997 boundaries of the bloc.
The US and NATO have told Putin to pound sand, and that NATO's "open door" policy is fundamental.
Which brings us to today. Ukraine wants to join NATO, while the threat implied by the buildup of Russian forces at the border couldn't couldn't be more clear: call it off or we're taking Kiev.