The waived sections of the law will allow the US to provide “defence articles and services” to forces within Syria allied to the US, the White House said on Thursday, a decision which is “essential to national-security interests”.
It is believed that the move will allow President Obama to arm the mainly Kurdish coalition fighters of the Syrian Democratic Forces (SDF), who are currently gearing up to retake the northern city of Raqqa from Isis.
Strengthening the SDF is strategically important for the US, giving them a future counter against President Bashar al-Assad’s forces, as US-backed rebel groups elsewhere in the country have crumbled.
The decision, however, is likely to further inflame US relations with Turkey, which views the Kurdish forces fighting against Isis as terrorists.
Turkey launched its own anti-Isis operation to clear the group from the border region in August, with a secondary motive of curbing any Kurdish appetite for expansion in the region.
US support for the Kurdish administration in Rojava is a source of tension between the Nato allies.
Speaking on Thursday, US State Department spokesperson Elizabeth Trudeau said that the US position on arming the Syrian opposition will not change even if the Syrian government is successful in retaking the contested city of Aleppo.
Whether US support for Sunni rebels in Syria’s six-year-old civil war will continue under President-elect Donald Trump’s administration is unclear.
Mr Trump has suggested that the US and the Syrian government could work together in order to combat the threat of Isis in future.