The EU Association Agreement with Ukraine triggered the coup d’état in Kyiv and the war in Ukraine.
There was no coup d’état in Ukraine in 2014. The Euromaidan protests were a spontaneous reaction among large parts of the Ukrainian population, ignited by the decision of former President Yanukovych not to sign the promised Association Agreement with the European Union in November 2013. The Maidan movement resonated with widespread discontent with corruption and mismanagement under Yanukovych’s rule.
It was not the European Union, but Russia, which triggered military conflict in Ukraine.
The Office of the Prosecutor of the International Criminal Court has stated that "the information available suggests that the situation within the territory of Crimea and Sevastopol amounts to an international armed conflict between Ukraine and the Russian Federation". This international armed conflict began at the latest on 26 February 2014 when the Russian Federation deployed members of its armed forces to gain control over parts of the Ukrainian territory without the consent of the Ukrainian government. The European Union stated in July 2014 that "arms and fighters continue flowing into Ukraine from the Russian Federation." Russian President Vladimir Putin admitted Russia's military presence in Ukraine in 2015.
See here for more information about the EU's support for Ukraine.