What is an unbiased view of the causes and trigger of the armed conflict in Ukraine, that started on the 24th of February 2022?

With “trigger” is meant the most recent cause. The one that was like “the straw that broke the camels back”, as the old saying goes.

Besides the most immediate cause: the trigger; causes can also be long term and short term causes.

Wikipedia articles are on the whole very informative, but they are often too long and general in nature to easily draw specialized conclusions from.

Is it possible to reach a consensus about the long and short term causes, and trigger of what pushed Putin over the edge, making him start the invasion of Ukraine?