VIENTIANE, Laos — Philippine President Rodrigo Duterte took a thinly veiled dig at the United States on Thursday, complaining that colonizers who killed many Filipinos are now raising human rights concerns with him.

President Barack Obama was among several world leaders who listened to Duterte’s brief speech at the East Asia Summit in the Laotian capital of Vientiane.

Obama earlier canceled a meeting with Duterte after the Philippine leader referred to him in comments to reporters as a “son of a bitch” and warned him not to discuss the deaths of thousands of suspects in an anti-drug campaign.

Two Philippine Cabinet officials said Duterte did not criticize any country or leader by name in his speech. Other diplomats who heard the speech, however, felt he was referring to the United States, which colonized the Philippines after defeating its former ruler, Spain.

An Indonesian diplomat said Duterte held up a picture of Filipinos killed in colonial times to underscore his point. The diplomat spoke to reporters on condition that he not be named because of the sensitivity of the issue.

Philippine officials refused to release Duterte’s remarks, which were not included in his prepared speech. The Department of Foreign Affairs in Manila said the president provided an explanation of how human rights records should be assessed in the context of the historical record.

“In the passionate intervention of President Duterte, he underscored the need to take a long historical view of human rights, mindful of the atrocities against the ethnic people of Mindanao,” the department said in a statement, referring to the southern Philippine region where American forces were involved in deadly clashes with Muslim Filipinos in the early 1900s.

Duterte, who assumed the presidency in June, has had an uneasy relationship with the U.S., his country’s longtime treaty ally. He has said he is charting a foreign policy that is not dependent on the U.S., and has moved to reduce tensions with China over rival territorial claims.

The tough-talking president has also blasted U.N.-appointed human rights experts and rights watchdogs who have expressed concerns over the extrajudicial killings of more than 2,800 suspected drug dealers and users since Duterte took office. More than 600,000 others have surrendered, apparently out of fear of being killed.

After the flap over Duterte’s earlier remarks, he and Obama met briefly on the sidelines of the Laos meetings and shook hands.

One Cabinet member, Jesus Dureza, said he asked Duterte how his talk with Obama went. “It was OK,” Dureza quoted Duterte as saying. “He told me, ‘we can talk some more at another time.'”

The summit ended with Laos turning over the chairmanship of the 10-nation Association of Southeast Asian Nations to Duterte, whose country will host the annual diplomatic gathering next year.