The two countries held a security dialogue on Friday and agreed to work towards resuming the talks between their diplomatic and defence chiefs, which a Philippine official said could be in the first half of the year, in Washington.
The nations are bound by a seven-decade-old Mutual Defense Treaty and various agreements that enable thousands of U.S. troops to conduct joint exercises in the Philippines, including live fire drills, amphibious assaults and counter-terrorism drills.
Those came under threat repeatedly in the past six years, however, after Duterte angrily vowed to withdraw from the security agreements, citing his mistrust and disdain for U.S. foreign policy and intent to be closer with China.
After Friday's dialogue, Daniel Kritenbrink, Assistant Secretary of State for East Asian and Pacific Affairs, sought to reassure the Philippines that the United States would come to its defence if under attack.
"Our ironclad alliance between the United States and the Philippines has contributed to the stability of the Indo Pacific region for more than 75 years and will only grow in importance in the coming years," Kritenbrink told a news conference.
The Philippines, a former U.S. colony, is among several countries at odds with China over its conduct in the South China Sea, with Manila furious over the constant presence of vessels in its exclusive economic zone that it says are manned by Chinese militia.
Duterte's administration had expressed doubts that the United States would come to the Philippines' defence in a future confrontation at sea with China's military.
The Philippine ambassador to Washington, Jose Manuel Romualdez, earlier on Friday confirmed in a text message the two countries were working to hold "2-plus-2" talks as early as March.
Asked what had changed since the departure of Duterte - under whom he served - and the arrival of Ferdinand Marcos Jr as president, he said "U.S.-Philippine relations is on an even keel, more coordinated".
Since Marcos took office last year after a landslide election win, several top U.S. officials, including Vice President Kamala Harris, have visited the Philippines to shore up ties, and discourage aggressive steps by China in the South China Sea and against self-ruled Taiwan.
(Reporting Karen Lema in Manila and David Brunnstrom in Washington; Writing by Ed Davies; Editing by Martin Petty, Kanupriya Kapoor)
By Neil Jerome Morales and Karen Lema
