'God told me to stop swearing'

Philippine President Rodrigo Duterte has made a solemn promise: no more swearing.

Duterte, who famously cursed the pope and used a slang term that translates as "son of a whore" in reference to President Obama, was flying back from Japan late Thursday, looking at a vast expanse of sky, listening to his colleagues snore, when he heard a voice say, "If you don't stop epithets, I will bring this plane down now."

"And I said, 'Who is this?' So, of course, 'it's God,'" he told Filipino journalists late Thursday.

"So, I promise God," he continued, "Not [to] express slang, cuss words and everything. So you guys hear me right always because [a] promise to God is a promise to the Filipino people."

Duterte, once nicknamed "the Death Squad Mayor," swept to power in July promising to "kill all" the country's drug users and dealers. Since then, more than 4,000 Filipinos have been killed in his self-proclaimed "war on drugs," according to police figures, either gunned down in raids or shot by masked assailants.

Rather than call for calm, the president has urged on the killing. He told troops to "massacre" criminals and promised police officers they would not be jailed for killing suspects on the job. Faced with criticism from the United Nations and others, he denied that the suspected drug users are human beings.