Syrian rebels backed by Islamic extremist fighters took full control of a sprawling military base Tuesday after a two-day battle that killed at least 35 government troops, an activist group said.
It was the second major base captured in the country's north by the rebels, who have been racking up victories in the area in recent weeks and making inroads farther south toward Damascus, seat of the government they are fighting to overthrow.
Fighters from jihadi groups including the Al-Qaeda-linked Jabhat al-Nusra were among those doing battle in the rebel ranks, according to the Britain-based Syrian Observatory for Human Rights, which relies on a network of activists inside Syria. Al-Nusra fighters appear to be among the most effective fighting forces on the rebel side, spearheading many of the recent gains.
The presence of the jihadi groups has raised concerns in the US and other nations that are supporting the opposition in Syria but do not want to see extremists gain power in the region. The US this week blacklisted al-Nusra as a foreign terrorist organization and said the group was part of Al Qaeda in Iraq.
The battle for the sprawling Sheik Suleiman military base, near the northern city of Aleppo, ended when the rebels took over the site's main compound and warehouses that housed a military research center, according to the Observatory. They had first breached the base perimeter on Sunday afternoon, after weeks of fighting with soldiers loyal to President Bashar al-Assad.
The Observatory said 35 soldiers were killed but did not give figures on rebel casualties from the battle.
Also Tuesday in Aleppo – the country's largest city and commercial center – four mortar rounds hit the predominantly Kurdish neighborhood of Sheik Maksoud, killing 11, including three children and two women, and wounding a dozen other people, the Observatory said.
The conflict started nearly 21 months ago as an uprising against President Assad, whose family has ruled the country for four decades. It quickly morphed into a civil war, with rebels taking up arms to fight back against a bloody crackdown by the government. According to activists, more than 40,000 people have been killed since March 2011.
The Obama administration is getting ready to tighten its ties to Syria's main opposition group, the newly formed Syrian National Coalition for Opposition and Revolutionary Forces, at an international conference on the crisis in Morocco this week. The move will pave the way for greater US support for those seeking to oust Assad.
The conference on Wednesday comes just days after the US blacklisted al-Nusra, freezing any assets its members may have in US jurisdictions and barring Americans from providing the group with material support.
The designation is largely symbolic because the group is not thought to have holdings or support in the United States, but officials hope the penalties will encourage others to take similar action and discourage Syrians from joining.
Jabhat al-Nusra is a shadowy group with an Al-Qaeda-style ideology whose fighters come from Libya, Tunisia, Egypt, Saudi Arabia, Iraq, the Balkans, and elsewhere. Many are veterans of previous wars who came to Syria for what they consider a new "jihad" or "holy war" against Assad.
But several hundred fighters from Jabhat al-Nusra – Arabic for "the Support Front" – have also been a valued addition to rebel ranks in the grueling battle for control of Aleppo. The group also has claimed responsibility for suicide bombings on Syrian government targets.
Jabhat al-Nusra is the largest grouping of foreign jihadis in Syria, and the rebels say they number about 300 fighters in Aleppo, as well as branches in neighboring Idlib province, the city of Homs and Damascus. US and Iraqi officials also have said they believe members of Al-Qaeda's branch in Iraq have crossed the border to join the fight against Assad.