The president of the United States, Barack Obama, canceled a meeting with the president of the Philippines, Rodrigo Duterte, in a rare rupture in diplomacy that comes in the wake of rising tension between the two allies over the new "war on drugs" in the Philippines.

The White House said last week that Obama was planning to meet with Duterte while traveling to Laos for a conference with Asian leaders, which was scheduled for tomorrow. The meeting would be the first between the two leaders after the inauguration of Duterte in June.

However, Obama has changed his plans, suggesting that he may have refused to meet in response to Duterte's comments on Monday about American questioning of the high number of extrajudicial killings in the Philippines. "It's better that you don't interfere, you son of a bitch, I will make you pay for it," Duterte said.

After President Obama arrived in Laos, the White House said the meeting with Duterte would not happen and that instead, Obama would meet with the president of South Korea, Park Geun-hye.

In a press conference about the meeting, Duterte blamed the United States – who colonized the Philippines until 1946 – for causing the country's problems. "The Philippines is not a vassal state – we have long since ceased to be a colony of the United States," the president said, rejecting the criticism of his fight against crime.

Since Duterte became president, the police have killed more than 2,000 people in the Philippines. The killings have led to allegations of abusing human rights and to criticism from the United Nations.

The United States and the Philippines are longtime allies, and Manila depends on U.S. support in its dispute with Beijing for areas of the South China Sea. Obama has said that the U.S. recognizes the challenges posed by drug trafficking, but has also argued that this issue must be addressed in accordance with international standards.