BEIRUT — In the span of a month, Syrian insurgents have routed government forces across the country's northwest, flushing them out of strongholds in a string of embarrassing defeats for President Bashar Al-Assad. The first to go was the city of Idlib, which fell to opposition fighters at the end of March, followed by the strategic town of Jisr Al-Shughour last week and the Qarmeed military base on Monday. Troops are now under fire at the few remaining outposts still in government hands. The disintegration of government forces in Idlib province, coupled with recent losses in southern Syria, has punctured the notion that Assad is on his way to defeating the four-year-old rebellion and undermined his claim to be a bulwark against Daesh (so-called IS) group, which had eclipsed the rebels over the past year. The campaign also points to a new unity and assertiveness within the constellation of opposition forces, which has long been riven by infighting. And it has exposed the government's fundamental weaknesses — including lack of manpower, battle fatigue and a heavy reliance on Iran and other allies. "It's really indicative of some huge problems the regime has," said Noah Bonsey, a Syria analyst for the International Crisis group. "What we're seeing now is the best evidence yet of a trend we've already known about: the regime's attrition rate is quite high and it can't replace the soldiers and militiamen that it loses with equally effective Syrian manpower." Now in its fifth year, Syria's conflict has killed more than 220,000 people and injured over 1 million. The relentless bloodshed has left the government scrambling to find recruits to fill its ranks, including by trying to curb widespread draft-dodging. The government has consistently focused on what it considers the territory key to its survival: the heavily populated corridor running from south of Damascus up to the city of Homs and over to the Mediterranean coast. Rebels and the Daeshhave carved off most rural areas to the north, east and south. But even with the narrow focus on major cities and highways, the government has relied on the Lebanese militant group Hezbollah and Iran-backed foreign fighters to gain and hold territory. And it can only count on its allies' support in the corridor where Hezbollah and Iran also have strategic interests. In peripheral areas like Idlib, the increasingly beleaguered troops have been on their own. Most of Idlib province — save its capital and a few smaller towns and villages — has been out of government hands for years. Assad may be calculating that the cost of keeping the province is greater than the price of losing it. — AP