Correction: An earlier of the article incorrectly implied that Tel Aviv is the seat of the Israeli government. The Israeli government is based in Jerusalem. This version has been corrected.

Israeli soldiers stand atop tanks in the Golan Heights near Israel's border with Syria on Wednesday. (Ronen Zvulun/Reuters)

— Israeli warplanes attacked Syrian military positions Wednesday in retaliation for a bombing the previous day, in the most serious confrontation between the two foes since the Syrian conflict erupted three years ago.

Syria said one of its soldiers was killed and seven were injured when three army positions near the town of Quneitra were struck on the Syrian side of the cease-fire line between the two countries in the Golan Heights.

Israel said that the targets were an army training facility, a military headquarters and an artillery battery, and that the raid was a response to a bombing along the line Tuesday that injured four Israeli soldiers.

The attacks sent tensions soaring in the already strained area, where Syrian troops and militia allies are battling rebels with a variety of allegiances who are intent on unseating Syrian President Bashar al-Assad. Stray shells have struck Israel on a number of occasions and Israel has retaliated with artillery strikes to deter the fire, but this was the first direct confrontation between the two militaries across the line.

Lt. Col. Peter Lerner, an Israeli army spokesman, said Israel did not know whether the Syrian army, its ally Hezbollah or the rebels they are fighting may have been responsible for planting the bomb. But Israel holds the Syrian army responsible, he said.

The blue marker shows the location of Quneitra.

Israeli Defense Minister Moshe Yaalon went further, accusing Syria’s government of collaborating with “terrorists” to plant the bomb and warning that the situation could escalate if there are more attacks.

“We hold the Assad regime responsible for what happens in its territory, and if it continues to collaborate with terrorists striving to hurt Israel, then we will keep on exacting a heavy price from it and make it regret its actions,” Yaalon said.

Addressing the Israeli cabinet, Prime Minister Benjamin Netanyahu also directly blamed Syria. “Our policy is clear. We hurt those who hurt us,” he said. “Syrian elements not only allowed but also cooperated in the attacks on our forces.”

Syria’s military command issued a counterwarning, accusing Israel of seeking to escalate tensions in order to take attention from the Syrian government’s recent advances against rebel fighters.

The strikes offered “a dose of moral support to the terrorist gangs tumbling under the Syrian Arab Army’s strikes,” the Syrian military command said in a statement carried by the official news agency SANA.

“Repeating these aggressive acts would jeopardize the region’s security and stability and make it vulnerable to all options,” the statement warned.

Although Israel has carried out numerous airstrikes against Syria over the past year, it is unusual for either party to acknowledge such an event, and the public statements seemed to underscore the seriousness of the latest confrontation.

The estimated death toll from the violence in Syria is more than 146,000 as the conflict enters its fourth year. The Post's Liz Sly explains the impact on the region and what we can expect moving forward. (The Washington Post)

Previous Israeli attacks were aimed at preventing deliveries of sophisticated weapons from Syria to the Shiite Lebanese Hezbollah movement, which Israel fought in a 2006 war, but Wednesday’s airstrikes raised tensions directly between Jerusalem and Damascus in an area they last fought more than four decades ago.

The Golan Heights has been administered by Israel since it captured the territory from Syria in 1967. The cease-fire line, a demilitarized zone patrolled by the United Nations, was established to keep the foes apart after the 1973 war.

Speaking at a meeting of his Likud party’s faction in the Israeli parliament Tuesday night, Netanyahu said that the situation in the Golan Heights was becoming a serious threat to Israel.

“The area is filling up with jihadist and Hezbollah militants, posing a new challenge for Israel,” he said. “In recent years, we were able to maintain quiet despite the civil war in Syria. Now we have to act firmly to maintain the security of Israel.”

The increased frequency of roadside bombs and stray rockets fired into Israeli territory is a growing concern, said a senior Israeli military official stationed in the northern border region. He spoke on the condition of anonymity because the subject is sensitive. Last Friday, a similar explosive device was detonated but with no injuries, and Israel implicated Hezbollah.

“Israel does not really care who did this, but it will not allow people to shoot at us or blow up side charges,” said Mordechai Kedar of the Begin-Sadat Center for Strategic Studies at Bar-Ilan University.

He said an escalation was possible because the situation in Syria is deteriorating and “there are those who would like to drag Israel into the war.”

“The question is, what is the price? If they know that the price they have to pay might be high, then maybe they will leave Israel alone,” Kedar said.

A rebel spokesman based on the Syrian side of the line accused Syrian intelligence of planting the bomb that wounded the Israeli soldiers in collaboration with local members of the National Defense Force, a paramilitary organization formed to support the army. Hezbollah does not have a presence in the Golan, but some of the paramilitaries are Shiite and have relations with Hezbollah, he said.

He said the Syrian government wants to implicate the rebels in order to draw Israel into a fight against them.

“This is an attempt to provoke Israel into attacking the rebels,” said Col. Al-Murabit, who asked to be identified by his nom de guerre for his safety. “But Israel knows who really planted this bomb and . . . we are happy they have intelligence to find out the real attacker.”

Neither Syria nor Israel has an interest in a direct confrontation across the cease-fire line, which remained peaceful for four decades until the 2011 revolt in Syria sent ripples of instability across the region.

Amos Yadlin, a former chief of Israeli military intelligence, told Army Radio that there was “no desire for escalation” on Israel’s part. “There is no spillover here,” he said.

Since the start of the uprising in Syria three years ago, Israel has invested more than $57.3 million in a state-of-the-art border fence in the Israeli-occupied section of the Golan Heights. Israel announced Wednesday it would reinforce its outposts there in order to prevent future attacks.

Sly reported from Beirut. Ahmed Ramadan and Loveday Morris in Beirut contributed to this report.