WASHINGTON — President Bashar Assad’s forces have resorted to firing ballistic missiles at rebel fighters inside Syria, Obama administration officials said Wednesday, escalating a nearly two-year-old civil war as the government struggles to slow the momentum of a gaining insurgency.
Administration officials said that over the past week, Assad forces for the first time had fired at least six Soviet-designed Scud missiles in the latest bid to push back rebels who have consistently chipped away at the government’s military superiority.
In a conflict that has killed more than 40,000 Syrians, the government has been forced to shift from reliance on troops to artillery, to airpower, and now to missiles as the rebels have taken over military bases and closed in on the capital, Damascus. The escalation has not changed Washington’s decision to avoid military intervention in Syria — as long as chemical weapons are not used — but it did prompt a rebuke from Washington.
“As the regime becomes more and more desperate, we see it resorting to increased lethality and more vicious weapons moving forward, and we have in recent days seen missiles deployed,’’ said Victoria Nuland, a State Department spokeswoman.
President Obama has said that the use of chemical weapons would cross a ‘‘red line,’’ implying that it might lead to a US military response.
Assad’s decision to fire Scuds — not known for their precision — inside his country appears directly related to the rebel ability to take command of military bases and seize anti-aircraft weapons. The Scuds have been fired since Monday from the An Nasiriyah Air Base, north of Damascus, and are believed to have carried a low-explosive warhead, according to US officials familiar with the classified intelligence reports about the attacks. The target was the Sheikh Suleiman base north of Aleppo that rebel forces had occupied.
The development may also represent a calculation by the Syrian leadership that it can resort to such lethal weapons without the fear of international intervention, partly because Washington had set its tolerance threshold at the use of chemical weapons. Obama has never suggested that the United States would take action to stop attacks against rebels and civilians with conventional weapons.
“This may be another example of the unintended consequence of the red line the administration has drawn with regard to chemical weapons,’’ said Joseph Holliday, a former Army intelligence officer and a senior analyst at the Institute for the Study of War, a nongovernmental research group. ‘‘Assad views every weapon short of chemicals as fair game.’’
The disclosure about the Scuds came as representatives of more than 100 nations gathered in Marrakech, Morocco, for a conference intended to give a political boost to the Syrian opposition, which is formally known as the National Coalition of Syrian Revolutionary and Opposition Forces. It came amid an increase in violence in Syria, including reports of a new massacre of about 100 Alawites, Assad’s sect, and a massive bombing in the capital.
Obama, in an interview Tuesday with ABC News, formally recognized the coalition as the legitimate representative of the Syrian people.
William Burns, the deputy secretary of state who led the US team to the Morocco gathering, said Wednesday that he had invited opposition leaders to Washington, including Sheik Admad Moaz al-Khatib, the coalition leader.
Khatib, however, took issue with a decision by the Obama administration to classify Al Nusra Front — one of several armed groups fighting Assad — as a foreign terrorist organization. Obama administration officials have said that the Nusra Front is an offshoot of Al Qaeda in Iraq.