The United States has decided to allow airstrikes to defend Syrian rebels trained by the U.S. military from any attackers, even if the enemies hail from forces loyal to Syrian President Bashar al-Assad, U.S. officials said on Sunday, Aug 2, according to Reuters.

The decision by President Barack Obama, which could deepen the U.S. role in Syria's conflict, aims to shield a still-fledging group of Syrian fighters armed and trained by the United States to battle Islamic State militants -- not forces loyal to Assad.

U.S. officials, speaking on condition of anonymity to confirm details of the decision, first reported by the Wall Street Journal, said the United States would provide offensive strikes to support advances against Islamic State targets.

The United States would also provide defensive support to repel any attackers, Reuters said.

The Pentagon and the White House declined to discuss the decision on rules of engagement or confirm comments by the unnamed U.S. officials.

White House National Security Council spokesman Alistair Baskey said only the U.S.-trained forces were being provided a wide range of support, including "defensive fires support to protect them" and pointed to Friday's U.S. airstrikes as proof.

"We won't get into the specifics of our rules of engagement, but have said all along that we would take the steps necessary to ensure that these forces could successfully carry out their mission," Baskey said.

The U.S. military launched its program in May to train up to 5,400 fighters a year in what was seen as a test of Obama's strategy of getting local partners to combat extremists and keep U.S. troops off the front lines.

The training program has been challenged from the start, with many candidates being declared ineligible and some even dropping out.