(CNN) US President Donald Trump's knack for diplomatic flattery will be tested in the Philippines on Monday when he and Philippines President Rodrigo Duterte meet for a state visit.

Trump's time in the Philippines will be a delicate balancing act between praise and frankness with Duterte, a leader whose war on drugs has led to thousands of extrajudicial killings and drawn international condemnation.

The visit, which will include stops at the Association of Southeast Asian Nations (ASEAN) and East Asia summits, comes at the end of the President's five-country, 13-day visit to Asia.

Trump plans to address human rights in his meetings with Duterte, senior administration officials told CNN.

But Trump's affinity for strongmen -- Russian President Vladimir Putin, Egypt's leaderr Abdel Fattah al-Sissi and Chinese Premier Xi Jinping to name a few -- will be tested by the Philippines' leader, a man so ruthless that he has even compared himself to Nazi leader Adolf Hitler

Human rights organizations say they are concerned that Trump will give Duterte a free pass on his drug war crackdown, by failing to mention the issue during his multi-day visit.

Duterte's 'unbelievable job'

Duterte has overseen a sweeping and violent crackdown on drug use in the Philippines during his time in office. International organizations, including the United Nations, have accused him of subverting justice and indiscriminate killing.

The Philippine strongman has embraced the image, though, and Trump, according to a leaked transcript obtained by The Washington Post , praised his crackdown during their first call, earlier this year.

"I just wanted to congratulate you because I am hearing of the unbelievable job on the drug problem," Trump said, not mentioning the thousands killed and international scorn.

A senior US official later tried to walk back Trump's comment, stating that Trump was merely acknowledging the US is combating its own drug problem, not condoning violence and human rights violations.

Duterte's past comments, though, could complicate how much Trump decides to embrace the world leader.

In 2016, after noting that Hitler slaughtered millions of Jewish people during the Holocaust, Duterte said: "There are 3 million drug addicts (in the Philippines.) I'd be happy to slaughter them."

Estimates of how many people have been killed in Duterte's war on drugs range from 6,000 to 10,000. Philippine police said last year that nearly 6,000 people had been killed in the violence.

Duterte has also repeatedly bragged about personally killing people when he was younger.

"When I was a teenager, I was in and out of jail. One fight there, another here," he said this week in Vietnam ahead of the recent Asia-Pacific Economic Cooperation (APEC) meeting . "At the age of 16, I killed someone."

When people in the crowd laughed, Duterte assured them he wasn't kidding.

"A person really. During a fight. Stabbing. That was when I was 16 years old, just because we just looked at each other," he said.

A spokesman for the Philippine President said later that he thought the comment "was in jest."

Turning the page on Obama

Leaders in the Philippines are eager for Trump's visit, viewing the President's arrival as a welcome change in American leadership given former President Barack Obama's relationship with Duterte was markedly frayed

Near the end of Obama's tenure, Duterte said Obama was a "son of a bitch" who could "go to hell ." Duterte later said he regretted the comment, but the White House canceled the meeting between the two world leaders at the East Asia Summit in 2016 over the comment.

Amy Searight, senior adviser of the Southeast Asia Program at the Center for Strategic and International Studies, told reporters before the trip that she expects Duterte to roll out the red carpet for Trump because he "sees this as an opportunity to somewhat reset US-Philippine relations."

"This could potentially bolster the bilateral relationship, including in our security partnership, which Duterte has been much less enthusiastic about than his predecessors," Searight said.

Philippine officials have also looked to highlight a connection between Trump and Duterte.

Philippine presidential spokesman Harry Roque told CNN before the visit that he sees Trump and Duterte as "very much alike."

"It's going to be very interesting because you have two individuals that are very much alike in their thinking, their language and demeanor, meeting for the first time," Roque said.

'Warm rapport'

A Trump administration official, in previewing the visit, stressed that Trump and Duterte have "a warm rapport."

"He's very much looking forward to his first in-person meeting with President Duterte," the official said.

Those comments angered human rights organizations, who see Trump's meeting with Duterte as validation from the United States that the controversial President's crackdown on drug use in the Philippines is acceptable.

Though Trump administration officials said the President would address human rights with the Philippine leader, national security adviser H.R. McMaster downplayed the importance of addressing human rights in Asia before Trump's trip.

"How much does it help to yell about these problems," he said. "What the President is doing is being effective."

A bipartisan group of lawmakers, though, were not satisfied with that response.

In a letter to Trump , members of the Tom Lantos Human Rights Commission on Capitol Hill urged Trump to address the extrajudicial killings.

"Human rights are fundamental," they wrote. "It is paramount that human rights violations not be the consequences of the Philippines' 'war on drugs.'"