Israeli warplanes and rockets struck nine targets in Syria early Monday in retaliation for a missile attack from Syria on Sunday that killed an Israeli teenager and wounded his father along the border in the Golan Heights.

A spokesman for the Israeli Defense Forces said Monday that Israel fired guided missiles from the ground and rockets from the air that hit sites in Syria, including a military command headquarters.

The Israelis would not say where in Syria the targets were. Over the past three years, Israel has attacked weapon transfers in Syria that it says were intended for the Lebanon-based Shiite military wing of Hezbollah. Israel also has fired at Syrian army targets after cross-border fire originated in Syria.

While the Syrian government did not comment on the airstrikes Monday, the Britain-based Syrian Observatory for Human Rights said that at least 10 Syrian soldiers had been killed. The organization’s Rami Abdurrahman said the Israeli strikes had destroyed two tanks, two artillery batteries and the headquarters of Syria’s 90th brigade, the Associated Press reported.

On Sunday, the Israeli teenager was killed and two other civilians were injured in what the Israeli military called an intentional cross-border attack from Syria into the Israeli-controlled Golan Heights.

The attack was the most substantial incident on Israel’s border with Syria since the conflict in that country erupted more than three years ago, said Lt. Col. Peter Lerner, a spokesman for the Israeli military. The Israeli army responded with tank fire on Syrian military targets across the border.

“This is not a case of errant fire but of an intentional attack,” Lerner said. He said that an antitank missile was fired but that it was still unclear who was behind the attack. Both the Syrian army and rebel groups fighting the government of President Bashar al-Assad are said to be stationed in the area.

Israeli news media identified the teenager as Mohammed Karaka, 13, from the Galilee village of Arraba. His father, a worker contracted by Israel’s Defense Ministry, had been delivering water to a construction site near the border fence when their vehicle was struck, the army said.

“This is a very severe event and marks another step in deterioration on the border with Syria,” said Eyal Ben Reuven, a former deputy head of the Israeli army’s northern command.

He said the attack was unsurprising because there have been several incidents in the past two years involving errant fire reaching into Israeli territory and explosive devices placed along the border fence.

In March, four Israeli soldiers were injured by a bomb planted along the border fence. Israel responded by striking Syrian army positions on their side of the Golan Heights.

Ben Reuven said it was likely that Israel would hold Syria responsible for Sunday’s attack, too.

“Syria is a sovereign country, and their mission is to keep the border with Israel quiet, like they did in the past,” he said.

On Sunday afternoon, the Israeli army filed a formal complaint with the U.N. peacekeeping force stationed along the Israeli-Syrian border, claiming that the incident was in breach of the cease-fire agreement between the two sides.

Israel has administered the Golan Heights since capturing the territory from Syria in 1967.

Since then and up until the start of the uprising in Syria in March 2011, the border had been fairly quiet. Over the past three years,however, Israel has invested almost $60 million in a state-of-the-art border fence to prevent spillover from the hostilities in Syria.