BEIRUT — Syrian rebels said they had overrun a major military checkpoint in Deraa Friday and hoped it would allow them to capture the southern city, the cradle of their 27-month-old uprising. Activists uploaded video showing fighters blowing up two high-rise buildings that had flanked the army post, flattening the entire area in a cloud of dust. The Syrian conflict began in Deraa as a peaceful protest movement against President Bashar Al-Assad's rule, but has spread across the country and degenerated into civil war. More than 100,000 people have died, according to the British-based Syrian Observatory for Human Rights, which works with a network of activists across Syria. Rami Abdulrahman, the head of the observatory, said the fall of the army post was strategically significant for Deraa, where protesters first marched against four decades of Assad family rule from the city's Omari mosque in March 2011. “Now the army is under threat there. The rebels haven't liberated all of the old city. There are still two neighborhoods with soldiers, but this could change the balance of power there,” Abdulrahman told Reuters. Local opposition activists were more upbeat, saying rebels had destroyed nearly all the military's 48 posts in the city and had forced soldiers to retreat. “This means Deraa's old city is liberated. It is a big deal for all Syrians: the heart of the revolution has been freed,” said an activist called Ammar, speaking by phone. The Omari mosque, which served as a gathering point and makeshift clinic when protests began, was also recaptured but has been nearly destroyed by tank and artillery fire, he said. Security forces had staged a bloody assault on the mosque from March 23-25, 2011, killing at least 31 people there. The capture of the Binayat post was one of the first major rebel victories in months in the south, where Assad's forces have been on the offensive, as they have in Damascus and Homs province. Before the government gains, Deraa, which is also the name of a province on the southern border with Jordan, had been an arms pipeline for rebels that stretched as far as Damascus. But army advances had cut several routes and rebels also complained that a US-Russian proposal for a “Geneva 2” peace conference, as well as Western fears of a rising Islamist current among the rebels, had stalled weapons transfers. Prospects for the conference have dimmed since Assad's forces, spearheaded by Lebanon's Hezbollah fighters, captured the town of Qusayr on the Lebanese-Syrian border this month. Gulf sources said they were given the green light to begin re-stocking rebels with heavy weapons after the United States announced it would provide the opposition with military support. Western powers are keen to ensure that only relatively moderate rebel units receive the shipments, as opposed to militant brigades, some linked to Al-Qaeda, that have become increasingly powerful among the armed opposition. Abdelrahman said Islamist fighters appeared to have led the latest battles in Deraa. — Reuters