A strongly-worded op-ed by the United States' former ambassador to Syria calls for the U.S. to arm the war-torn nation's moderate opposition and warns that Al Qaeda-aligned forces in the region are on the rise.

“More hesitation and unwillingness to commit to enabling the moderate opposition fighters to fight more effectively both the jihadists and the regime simply hasten the day when American forces will have to intervene against Al Qaeda in Syria," Robert S. Ford, who served from 2010 to 2014, wrote in the New York Times.

Ford says he resigned in February because he "found it ever harder to justify our policy" as the situation in Syria deteriorated.

"Al Qaeda offshoots that joined the war now pose a potential threat to our security," Ford wrote. "These extremists enjoy a sanctuary from which they may mount attacks against Europe or the United States."

The op-ed comes as a major outbreak of violence and unrest in northern Iraq -- where Al Qaeda-aligned insurgents effectively toppled the country's second-largest city -- is fueling concerns in Washington that security in Iraq is rapidly deteriorating, a little more than two years after U.S. troops left the country.

Ford believes the U.S. needs to supply military hardware such as mortars and rockets to weaken the Syrian government's airfields, while also supplying cash for small salaries and supplies of food, medicine and ammunition.

"To be sure, there is no military solution, but it is possible to salvage something in Syria by preparing the conditions for a genuine negotiation toward a new government," Ford said.

Click here to read more from the New York Times.