MANILA, Philippines -- Philippine President Rodrigo Duterte has sanctioned a bloody drug war that features extrajudicial killing. He called Barack Obama a "son of a whore." This week, he boasted that he murdered a man with his own hands.

All that may well go unmentioned in public by U.S. President Donald Trump when the leaders hold talks Monday.

Breaking with his presidential predecessors, Trump has largely abandoned publicly pressing foreign leaders on human rights, instead showing a willingness to embrace international strongmen for strategic gain. He has cozied up to autocrats such as Saudi Arabia's King Salman, Egyptian President Abdel-Fattah el-Sissi and Russian President Vladimir Putin. And earlier in this trip to Asia he made no mention of human rights during multiple appearances in Beijing with Chinese President Xi Jinping.

"Trump seems very comfortable with strongmen. It's not just that he won't criticize Duterte. I wouldn't be surprised if he patted him on the back," said Mike Chinoy, senior fellow at U.S.-China Institute at the University of Southern California.

Duterte's war on drugs has alarmed human rights advocates around the world who say it has allowed police officers and vigilantes to ignore due process and to take justice into their own hands. Government officials estimate that well over 3,000 people, mostly drug users and dealers, have died in the ongoing crackdown. Human rights groups believe the victim total is far higher, perhaps closer to 9,000.

"Human rights groups, I think, will be quite disappointed by the visit," said Amy Searight, director of the Southeast Asia Program at the Center for Strategic and International Studies. "It's unlikely that human rights or rule of law or due process are going to be topics that President Trump will raise."

Duterte has strenuously defended the violence and boasted of participating himself.

Late last year, he bragged that he personally pulled the trigger and killed three people years ago while serving as mayor of Davao City. And last week, while in Vietnam for an international summit, he said he took his first life years earlier.

"When I was a teenager, I had been in and out of jail, rumble here and there," Duterte said during a speech in Danang, where he briefly crossed paths with Trump on the sidelines of an international summit. "At the age of 16, I already killed someone."

He claimed he fatally stabbed the person "just over a look." His spokesman later tried to downplay the comment, saying, "I think it was in jest."

Trump has shown little interest in pressuring Duterte to rein in the violence, instead saluting him during a May phone call.

"I just wanted to congratulate you because I am hearing of the unbelievable job on the drug problem," Trump told Duterte, according to a transcript of the conversation that later leaked. "Many countries have the problem, we have a problem, but what a great job you are doing and I just wanted to call and tell you that."

Trump also criticized Obama during the call, noting that his predecessor "did not understand" the drug problem the Philippines faces. Meanwhile, Duterte was openly critical of Obama in the final year of his presidency, including cursing his name.

White House officials have suggested there is a strategy behind Trump's flattery of Duterte.

Advisers have said that while Trump is unlikely to publicly chastise the Philippine president, he may offer criticisms during private meetings. Trump would plan to hold his tongue in public in order not to embarrass Duterte, whom he is urging to help pressure North Korea and fight terrorism, and to avoid pushing him into the arms of China.

"If the administration is not going to care about human rights in China, why would you care in the Philippines?" asked Gordon Chang, Asia expert and author of "Nuclear Showdown: North Korea Takes On the World." He said the "logical thing to do is keep them close and not let Duterte flirt with China. In our struggle with China, we need all the friends when we can get."

Duterte has seemed less committed to the strategic partnership with the U.S. Searight said a good relationship is "vital to the United States given its location on the South China Sea and the enhanced access that the American military has gotten in recent years with the Philippines."

White House aides have suggested that Trump's strategy has worked before, pointing to his interactions with el-Sissi. Trump refrained from chastising the Egyptian leader but worked with him behind closed doors to help engineer the release of American prisoner Aya Hijazi in April.

Trump dismissed the notion that he buddied up to dictators. He said Saturday he has great relationships with all sorts of leaders, "every person in that room today," after leaving a summit in Vietnam attended by Duterte and Putin, among others.

Human rights groups have expressed dismay at Trump's public silence, believing that the spotlight an American president can shine on human rights abuses overseas can rally pressure on an authoritarian regime to change its ways.

"In the old days, we used to call on the U.S. government to raise human rights issues during these trips," said John Sifton, Asia advocacy director at Human Rights Watch. But given the administration's lack of credibility in raising human rights abuses, he said, they have pivoted to a different tack, focusing on international attention.

"We haven't given up," Sifton said.

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Associated Press writer Jill Colvin contributed to this report.