President Barack Obama is threatening to cancel a meeting with Philippine President Rodrigo Duterte after the fiery political figure called the U.S. president a “son of a bitch.”

According to the Associated Press, Duterte demanded that Obama be respectful during the G-20 summit. Otherwise, he said, “son of a bitch, I will swear at you in that forum.”

Duterte was referring to a potential discussion about his violent war on the drug cartels, killing over 2,400 people in the process.

During a press conference in China at the G-20 summit, Obama hinted that the meeting between himself and Duterte could be canceled.

“What I’ve instructed my team to do is to talk to their Philippine counterparts to find out is this in fact a time when we can have constructive, productive conversations,” he said.

Obama said that the United States would “always assert” the need for due process in prosecution of drug criminals, citing basic international norms. He added that he would bring it up in a meeting, despite Duterte’s comments.

He described Duterte as a “colorful” leader, but reasserted the United States close relationship with the Philippines.

“I have seen some of those colorful statements in the past so clearly he’s a colorful guy,” Obama replied to reporters, after he was asked about the comments during a press conference in China at the G-20 summit.