President Donald Trump told Philippines President Rodrigo Duterte that he was "doing an amazing job" with his brutal drug war crackdown and informed him that the U.S. had two submarines off the Korean peninsula, according to a recently-released transcript of the two leaders' phone call last month.

"You are a good man," Trump told Duterte in the April 29 call, which was highly controversial when placed. "Keep up the good work. You are doing an amazing job."

"I just wanted to congratulate you because I am hearing of the unbelievable job on the drug problem," Trump said. "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."

"Thank you Mr. President," Duterte replied. "This is the scourge of my nation now and I have to do something to preserve the Filipino nation."

Trump called the Philippines strongman—whose regime has killed thousands of people since he took office last June, and who previously bragged about killing suspected criminals while serving as mayor of Davao city—to invite him to visit the White House, which Trump's chief of staff Reince Priebus later defended as a sign of international cooperation on addressing issues with North Korea.

That apparently included the U.S. president informing Duterte that there were two American submarines off the Korean peninsula.

"We can't let a madman with nuclear weapons let on the loose like that," Trump told Duterte, referring to North Korean leader Kim Jong-Un. "We have a lot of firepower, more than he has times 20, but we don't want to use it."

"We have a lot of firepower over there. We have two submarines—the best in the world—we have two nuclear submarines—not that we want to use them at all," he continued.

The transcript was reportedly produced by the Philippine Department of Foreign Affairs and its authenticity confirmed by "well-placed sources" at the department and the Palace, said the Manila-based news outlet Rappler, which collaborated with The Intercept to publish it.

It comes just as Duterte separately declared martial law on the island of Mindanao, in the southern part of the Philippines, where government forces are in conflict with rebels.

He warned that he may expand military control throughout the nation.

"If I had to kill thousands of people just to keep Philippines a thousand times safer, I will not have doubts doing it," he said.

Duterte's relationship with Trump is much warmer than with former President Barack Obama, whom the Philippines leader called a "son of a whore" for criticizing his murderous regime.

During their phone call, Trump appeared to remind Duterte that he supported his position on the drug war.

"I understand that, and fully understand that," he said in the transcript, "and I think we had a previous president who did not understand that, but I understand that and we have spoken about this before."