WASHINGTON (AP) — The crisis over Crimea is more than a dispute over whether the strategic Black Sea peninsula should be considered Russian or Ukrainian. At its root is a deeper issue: Russia’s simmering anger over its treatment by the West since the 1991 breakup of the Soviet Union.

Russia’s biggest grievance has been the absorption into the NATO alliance not only of former Soviet allies, such as Poland and Romania, but also three republics that were part of the Soviet Union: Latvia, Lithuania and Estonia. The last straw was a European Union move to draw Ukraine closer to the West through a political association agreement. That set off a chain of events that led to the ouster of Ukraine’s pro-Russian president and, ultimately, to Russia’s annexation of Crimea.