Event: Sentinel Uprising
In 2018, the global mutant-hunting AI robots called Sentinels went berserk. Over the course of a single month, thousands of metahumans and baselines alike were killed or badly injured, with many put into unlawful confinement and detention centers. The worst of the impact was in the European nation of Sokovia, which had become a epicenter for refugee and displaced metahumans fleeing increasing anti-meta sentiments.
When the rampage ended, Sokovia was virtually destroyed. The United States sponsored the Sokovian Accords in recognition of the excesses of the world governments. Only a handful of UN Nations refused to sign, including China, several other Baltic states, and three African nations.
A team of X-Men covertly sabotaged and destroyed several Sentinel production facilities. They tracked a command module emitting a rogue signal into space and located a facility on Enceladus, a moon of Saturn. There, they met Sentinel Alpha, an advanced prototype AI that had developed self-awareness. A fierce battle followed, and Sentinel Alpha was destroyed. The base was sabotaged and destructive programs were sent out to all remaining Sentinels, crippling the rest of the fleet.