Back in 1994, Ukraine signed "Budapest Memorandum for Security Assurance" . By signing that they gave in their nuclear arsenal in exchange for European's commitment in protecting their sovereignty and territorial integrity.
Fast forward 2014, successfully ousted russian puppet Yanukovich, and Putin seized Crimea. Germany concerned with Putin's boner for imperialism, promised to strive for drastically reduce european's dependence on Rooskie gas pipelines. The only thing that Germany achieved under Merkel was to proscrastinate on this agenda, and nowadays they actually negotiated another russian pipeline.
For this kind of bullshit I can understand any modern surge in nationalism, despite of globohomo disdain for it. When It comes of geopolitics, countries should learn the lesson poles learnt through blood: "trust no one, specially Europe".
If Ukraine would've kept Its nuclear weaponry and refused to sign that memo, We would have wake up in the morning with drastically different news on this conflict today.