Malacañang honored the 58 soldiers and policemen who died fighting extremists in Marawi City in the afternoon broadcast of all local TV and radio stations on Independence Day.
The cooperation between the longtime allies in the battle is significant because Duterte, who came to power a year ago, has taken a hostile stance towards Washington and has vowed to eject USA military trainers and advisers from his country. Duterte set a three day deadline earlier in June, when the military initially estimated it would take just a week to clear militants from the city.
The U.S. military has deployed a spy plane at Manila's request to help provide surveillance to troops battling militants still holed up in a few buildings in Marawi with an unspecified number of civilian hostages.
The Pentagon has no permanent presence in the Philippines but for years has kept 50 to 100 Special Forces troops in the south of the country on rotational exercises.
Major General Ganip Warsito, the regional military chief overseeing the closest areas to neighbouring Philippines said Indonesia army, navy and air force have deployed extra troops to boost security in the region.
The terrorists attacked the city on May 24, and is still well in control of the area despite attacks made by government forces.USA forces have been requested to provide assistance to end the terrorist attack.
A US P3 Orion surveillance aircraft flying over Marawi City as government troops continue their assault against insurgents from the Maute group, who has taken over large parts of the city, June 9, 2017.
Calida defended President Rodrigo Duterte's decision to declare martial law in the entire southern Mindanao region to deal with the Marawi crisis.
Her sons, Omar Romato Maute and Abdullah Romato Maute, are suspected of conspiring with Isnilon Hapilon, leader of the Islamist group Abu Sayyaf, in masterminding the attack on Marawi City.
As the conflict intensifies, the U.S. embassy in Manila said on Saturday American forces were providing assistance to the Filipino troops, although it declined to give details for security reasons.
"The fight against terrorism is not only the concern of the Philippines or the United States but it is a concern of many nations around the world", Abella, the presidential spokesman, said.
"The Philippines is open to assistance from other countries if they offer it", according to the statement, cited by Reuters.
Thus, it was with some irony that it has now emerged that USA forces are helping Philippines to battle the Isis-linked fighters entrenched in Marawi.
Asked to comment on how much of the lakeside town was still occupied as the siege entered its fourth week, Lieutenant General Carlito Galvez, head of military command in Western Mindanao, told Reuters it was 20%.
'LAND BASE' For his part, Foreign Affairs Secretary Allan Peter Cayetano said in Independence Day rites in Manila that the militants had planned to take over at least two or three cities in Mindanao.
Some civilians were being held as human shields, while others hiding in their homes fear capture by the militants and have no running water, electricity or food, said Zia Alonto Adiong, a politician involved in evacuation efforts.
Authorities have detained Cayamora and Farhana Maute, parents of brothers Omarkhayam and Abdullah who are leading Maute group attacks in Marawi City.