The EU didnt take the threat seriously because they couldnt comprehend Putin jeapordising trade relationships with the rest of Europe. Putin in turn thought tha

The EU didnt take the threat seriously because they couldnt comprehend Putin jeapordising trade relationships with the rest of Europe. Putin in turn thought that Europe would roll over like they did with Crimea, they'd also be scared to lose access to Russian gas. Both sides were wrong. Putin was stupider than the EU realised and Russian gas was not as indispensible as he though it was.