US Special Forces have joined an ongoing battle against ISIS militants in the southern Philippines town of Marawi, following months of tension between Washington and Manila.

The Philippines military said in a statement on Saturday that US forces are not fighting, but providing technical assistance to end the siege of Marawi City, which is now in its third week.

According to US embassy, Washington offered support at the request of the Philippines government; it has however refused to provide further details.

Media reports said a US P3 Orion surveillance plane was seen flying over Marawi on Friday.

Philippine troops are struggling to dislodge at least 200 militants, who are holed up in the city of Marawi since last month. An estimated of 500 to 1,000 civilians are trapped in the town, some of them are being used as human shields.The US so-called technical support to the Philippines military is now happening despite strained ties between Washington and Manila and former calls by President Rodrigo Duterte that he wanted US troops out of his country.

The US that has had a logistical military presence in the Philippines, however, has pledged to remain “committed to our pursuit of shared objectives” in keeping with the “seven-decade alliance between our two countries.”

Duterte repeatedly clashed with Washington over his anti-drug campaign, which was criticized by the US and rights groups.

US President Donald Trump, however, invited Duterte to the White House in April saying, “The Philippines is very important to me strategically and militarily.”