In a private phone call a week ago, President Donald Trump told Nicolás Maduro that he had to go.

By that point, an armada of U.S. warships was floating off Venezuela's shores. A CIA team had crept into the country, tracking Maduro's movements and habits: where he slept, what he ate, where he traveled.

The Venezuelan president opted to stay put — and his defiance set in motion the final phase of a secret and risky plan to evict him by force.