Bolivia had been enjoying some well earned quiet in recent days. South America's poorest nation seemed on the verge of a civil war last year between forces loyal to President Evo Morales, Bolivia's first indigenous head of state, and those aligned with the country's white elite. But after a new Constitution was finally approved in January, and an agreement was struck earlier this week to hold new presidential and congressional elections, calm seemed at hand.

It was shattered before dawn on Thursday when authorities uncovered what they insist was an assassination plot against Morales. At 4:30 a.m., police surrounded the Hotel de las Americas in downtown Santa Cruz, the capital of Bolivia's anti-Morales east. They'd been tipped about armed occupants in two of the rooms; and when...