An Israeli soldier from the Golani Brigade sleeps as others, seen through a black netting, pray close to the ceasefire line between Israel and Syria on the Israeli occupied Golan Heights. (BAZ RATNER/Reuters)

In blunt language marking a turn away from diplomatic caution, Israel warned the Syrian government Tuesday that it “would suffer the consequences” if it continued to press attacks, hours after Syrian and Israeli troops exchanged fire along the cease-fire line in the occupied Golan Heights.

After an Israel Defense Forces jeep was hit by machine-gun fire from a Syrian military post on the cease-fire line, a potential flash point for spillover from Syria’s civil war, Israel “returned pinpoint fire at the source,” an Israeli military spokesman said.

Israeli defense officials said the military responded with a short-range, antitank Spike missile.

“We will not allow the area of the Golan Heights to turn into an easy target for Syrian attacks,” IDF Chief of Staff Benny Gantz said. “Last night, Syrian positions fired three times while we were patrolling along the border fence. We’ve had enough,” said Gantz, addressing Syrian President Bashar al-Assad. “We are seeing things happening in Syria — the transfer of military equipment, Assad issuing warnings, talking, leading and encouraging the expansion of actions against the state of Israel at various levels, including the Golan Heights.”

If Assad follows through on the threats, the chief of staff added, “he will suffer the consequences.”

Interactive Grid: Keeping track of the conflict in Syria through videos, images and tweets.

Gantz’s remarks, delivered at Haifa University’s National Security Studies Center and translated into English by the newspaper Haaretz, were among the most explicit on-the-record warnings by Israeli officials to Syria since the conflict in that country began more than two years ago.

The Israeli military also released a one-minute video, filmed in grainy black and white with a night-vision camera, purporting to show three shots fired from the Syrian army outpost, followed by an explosion set off by Israeli forces.

Although several stray mortar and rocket rounds have been fired from Syria into the Israeli-
occupied Golan Heights, most of the incidents were considered accidents. The intentional targeting of Israeli forces, as occurred Tuesday, has been rare.

The Syrian army released a statement earlier in the day asserting that its forces “destroyed an Israeli vehicle with everything that it had in it.”

The Syrians said the jeep was attacked only after it crossed the cease-fire line in the direction of Bir al-Ajam, one of many villages on the Syrian side that has changed hands in fighting between rebels and Assad’s forces in recent months.

“The jeep was on the Israeli side of the line,” said Capt. Eytan Buchman, an IDF spokesman, adding that one bullet struck the vehicle and that the soldiers were unharmed.

“We will not remain silent about shots fired from Syria into our territory,” Defense Minister Moshe Yaalon told Israel Army Radio. “Our policy is very clear in regards to Syria. We do not plan to get involved in the civil war there, but the situation on the Golan Heights might not allow this.”

For 40 years, the cease-fire line has been quiet. But in recent months, U.N. peacekeepers in the buffer zone have been kidnapped, and later released, by Syrian rebel groups in the area. The rebels said the U.N. troops were detained for their own protection.

Relations between Syria and Israel have worsened since recent airstrikes in Syria said to be carried out by Israel, targeting weapons bound for the Lebanese Shiite political and military organization Hezbollah. Assad has accused Israel of aiding the rebel forces.

In Syria, airstrikes and heavy clashes continued in Qusair for a third day Tuesday, as the government attempted to wrest back control of the strategic western town.

Ringed by government forces, as many as 20,000 civilians are estimated to be trapped inside the town, which lies just across the Lebanese border and has been under rebel control for more than a year. UNICEF said Tuesday that it was “extremely concerned” about the safety of children and civilians in the town.

Gaining control of Qusair could be a game-changer for Assad’s government, whose forces have been backed by Hezbollah militants in the assault.

The government and the opposition have given conflicting accounts of the extent to which the pro-Assad forces have penetrated the town.

In a statement Tuesday, the government claimed to have “restored stability” in most of Qusair, inflicting “heavy losses” on rebels, but videos posted online by the opposition showed evidence of a fierce ongoing battle.

Ahmed, an activist based in the town who gave only one name out of security concerns, said opposition forces were holding firm. “The Free Syrian Army haven’t given a meter,” he said.

Ahmed said two airstrikes Tuesday morning had killed three people, including a mother and her two children. That assertion appeared to be supported by a gory video posted online by rebel activists that showed the bodies of two young boys, who the opposition said had been killed in the assault.  

The increasing entrenchment of Hezbollah — which was formed to fight Israel — in a conflict with fellow Muslims is stirring controversy at home in Lebanon. Three Hezbollah militants died Tuesday of wounds suffered in the Qusair assault, according to the Britain-based Syrian Observatory for Human Rights, taking the total number of deaths among the group’s fighters to 31. The Observatory said that at least 68 Syrian rebels and nine soldiers have been killed over the three days of fighting in Qusair.

The deepening violence in the town comes as Russia and the United States scramble to organize peace talks between representatives of Assad’s government and the opposition, scheduled for next month. 

After two days of consultations in Madrid, members of the Syrian Opposition Coalition set out a list of demands for the talks, according to the group’s former president, Mouaz al-Khatib. They include a guarantee that Assad will stand down — a condition the government has rejected. 

Morris reported from Beirut.