MANILA/MARAWI CITY, Philippines (Reuters) - U.S. forces are providing the Philippines with technical assistance to end a siege of the southern town of Marawi by militants allied to Islamic State but it has no boots on the ground, the Philippines military said on Saturday.

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The seizure of Marawi by hundreds of fighters who have sworn allegiance to Islamic State, including dozens from neighboring countries and the Middle East, has fueled concern that the ultra-radical group is gaining a foothold in Southeast Asia.

Earlier a U.S. embassy spokesperson in Manila told Reuters that, at the request of the Philippines government, special operations forces were helping liberate the town, part of which has been occupied by hundreds of militants since May 23.

In Marawi, military spokesman Lieutenant Colonel Jo-Ar Herrera confirmed the U.S. assistance, telling a news conference: “They are not fighting. They are just providing technical support.”

A U.S. P3 Orion surveillance plane was seen flying over the town on Friday, according to local media reports.

Until now there had been no confirmation that the Philippines had sought U.S. support in the battle for Marawi City on the island of Mindanao, which is in its third week.

The assistance comes after months of strain between the two long-time allies that was stoked by Philippines President Rodrigo Duterte’s hostility toward Washington and his pledges to throw U.S. troops out of the country.

Washington deployed special forces soldiers to Mindanao in 2002 to train and advise Philippine units fighting Abu Sayyaf militants in a program that once involved 1,200 Americans.

It was discontinued in 2015 but a small presence remained for logistics and technical support.

The United States and the Philippines have been allies for decades. Their relationship provided Washington with a strategic foothold in Asia, and offered Manila a shield against China’s assertiveness in the region.

But Duterte has openly scorned the alliance, seeing it as an obstacle to a rapprochement with China, and has repeatedly lambasted Washington for treating his country as a lackey.