Two things catch the eye in the office of Joselito Esquivel, a police colonel enforcing a national crackdown on drugs in the Philippines' most crime-ridden district: a pair of boxing gloves in a display cabinet and an M4 assault rifle lying beside him.

"It's all-out war," the Quezon City officer says of a spike in killings of suspected drug dealers by police across the country since last month's election of Rodrigo Duterte, a tough-talking city mayor, as the country's president. "Duterte has already given the impetus for this massive operation."

Duterte has vowed to wipe out drug crime within six months but, according to Chito Gascon, head of the Commission on Human Rights (CHR), the aggressive rhetoric behind his promises has already instilled a sense of impunity among the police.