Colonel Lerner said that he did not know whether an explosive device, rocket, mortar round or tank fire was used, but that “it was fired directly from east to west,” and that Israeli soldiers later found a hole in the fence that demarcates the cease-fire line.

There have been several exchanges of fire in recent months in the Golan, which Israel captured from Syria in 1967 and later annexed but much of the world still considers occupied territory. In March, Israel bombed Syrian positions after an explosive device wounded four Israeli soldiers patrolling the frontier, and two weeks before that, Israeli forces fired at two men they said were planting a bomb on the Syrian side.

Another soldier was wounded in October by shrapnel from mortar shells fired across the cease-fire line.

Eyal Ben-Reuven, a reserve major general in the Israel Defense Forces and former deputy of its northern command, described Sunday’s attack as “another step of deterioration” in the long-quiet area where he said “the sky is becoming cloudy.” General Ben-Reuven said that rebels were probably behind the attack, but that Israel nonetheless held President Bashar al-Assad of Syria responsible and had fired at his military to “tell them: you have to control your area and stop this terror organization acting against Israel.”