The move represents a significant escalation in the fighting, which has already killed more than 40,000 civilians in a nearly two-year-old conflict that has threatened to destabilize the Middle East, and suggests increased desperation on the part of the Assad government.
One American official, who asked not to be identified because he was discussing classified information, said that missiles had been fired from the Damascus area at targets in northern Syria.
“The total is number is probably north of six now,” said another American official, adding that the targets were in areas controlled by the Free Syrian Army, the main armed insurgent group.
It is not clear how many casualties resulted from the attacks by the Scuds — a class of Soviet-era missiles made famous by Saddam Hussein of Iraq during the first Persian Gulf war. But it appeared to be the first that the Assad government had fired the missiles at targets inside Syria.
American officials did not say how they had monitored the missile firings, but American intelligence has been closely following developments in Syria through aerial surveillance and other methods, partly out of concern that Mr. Assad may resort to the use of chemical weapons in the conflict.
The Obama administration views the Assad government’s use of Scud missiles as a “significant escalation” of the conflict…