When Philippines President Rodrigo Duterte summoned his security chiefs to an urgent meeting one Sunday night last month, his mind was already made up.

His military and law enforcement heads had no idea what was coming: a suspension of the police force's leading role in his signature campaign, a merciless war on illegal drugs.

There was only one reason for the U-turn, three people who attended the Jan. 29 meeting said. Duterte was furious that drugs-squad cops had not only kidnapped and murdered a South Korean businessman, they had strangled him to death in the headquarters of the Philippines National Police itself.