"I am not aware of that until they arrived," Duterte told reporters in an interview during his visit with the wounded soldiers in Cagayan de Oro City.
But he said when he declared martial law in Mindanao due to the attack of the Maute militants in Marawi starting May 23, he gave the powers to the Defense department to decide on the matter.
"I'm not meddling," he said as he thanked US for its help.
While he also wanted to maintain his policy of no foreign interference, Duterte said the situation in Marawi was an exception because "there is war".
"We are not powerful. Maybe we do not have the technical expertise to do it," he added.
The Armed Forces of the Philippines admitted on Saturday that the US has been extending technical assistance in its operations against Maute. But the military has said the American forces were not participating in the actual combat.
Duterte also acknowledged that most members of the Philippine Army studied and trained in the US, thus, their sentiment is "pro-American."
While he had been critical with the US before, he said his "quarrel" was only with the State Department and with former President Barack Obama.
The State Department and Obama had been critical with Duterte's war on drugs due to the alleged extrajudicial killings of drug suspects.
But now, he said he was friend with US President Donald Trump.
Meanwhile, the Philippine military disclosed on Sunday that Maute had planned to do massive killings had it been successful in occupying Marawi City.
According to AFP chief of staff General Eduardo Ano, one of the captured members of the terrorist group revealed to the military that this was one of the instructions of Abdullah Maute, one of the leaders of the group, which pledged allegiance to the Islamic State of Iraq and Syria.
"Once they occupied Marawi, they will go to Iligan and killed as many as they can. They will kill as many non-Muslims as they can," he said in a press briefing in Cagayan de Oro City.
He said it was Maute's plan to show to the world that there was already an existing ISIS caliphate in the Philippines.
"They know that they need to establish a base in Asia and they chose Mindanao, particularly Lanao (del) Sur, as the base of ISIS here in Asia," he said.
Ano said the grand plan of the Maute brothers to attack Marawi and declare it as their caliphate failed because the people of the city did not welcome them.
"What they (were) expecting (was) the whole population of Marawil would welcome them just like what happened in Mosul," he said.
He said Abdullah's plan was the same as that of ISIS leader Abu Bakr al-Baghdadi's when he occupied Mosul in 2011.
He added the Maute brothers have a connection with Baghdadi who ordered them to attack Marawi.
"The (Mosul) attack was also (on) the first day of Ramadan and the plan of Maute is on the first day of Ramadan also, which is May 26, to start occupying Marawi, to attack 103rd Brigade and seal the whole Marawi and declared it as the first Islamic caliphate," Ano said. (Celerina Monte, Ella Dionisio/DMS)
