JERUSALEM -- Israeli tanks made a direct hit on Syrian artillery units on Monday, the army said, responding to mortar fire that fell near an army post in the Israeli-held Golan Heights.
It was the second consecutive day that Israel confronted fire along its border with Syria. On Sunday, a mortar shell crashed in from Syria, prompting Israel to respond with what its military described as "a warning shot" at a Syrian position across the frontier for the first time in 39 years.
On Monday, a military spokesman said that a mortar shell hit an open area in the vicinity of an Israeli army post in the central Golan Heights but caused no damage or casualties. In response, Israeli soldiers fired tank shells toward the source of the fire, hitting Syrian mobile artillery units, the spokesman said.
"The difference is that we confirmed a direct hit this time," the spokesman said, comparing Monday's exchange to the events on Sunday, when a stray Syrian mortar shell hit an Israeli military post in the Golan Heights. "Yesterday it was a warning shot. Today we fired toward the source of the fire."
Syrian government forces are battling armed rebels on the other side of the Israeli-Syrian armistice line, which has been in place for decades.
The direct strike by Israel on Syria's artillery unit was another example of how the conflict in Syria has escalated by spilling into neighboring countries. Hundreds of thousands of refugees have poured out of the country, with more than 408,000 in Turkey, Jordan, Lebanon and Iraq now registered with the United Nations. Shells fired from Syria have killed civilians in Lebanon, and in one episode last month, Islamic extremists attacked Jordanian soldiers on the border with Syria, killing a corporal.
On Monday, a Syrian MIG-25 jet bombed the rebel-held town of Ras al-Ain a few yards from the Turkish border, killing civilians, Syrian witnesses said. Five Turkish civilians were killed in October when a Syrian shell landed in Akcakale, another border town about 75 miles west of Ceylanpinar, an act that prompted the Turkish Parliament to revise engagement rules and allow the military to retaliate in case of a direct threat from the border region.
Israeli military officials have made it clear that Israel has no desire to get involved in the fighting in Syria. Israel had already filed complaints with the United Nations observer force that monitors the armistice agreement reached between the Israeli and Syrian forces after the 1973 war, and the United Nations has warned that the spreading violence could jeopardize the cease-fire between the two countries.
"We hope they get the message this time," Moshe Yaalon, Israel's minister of strategic affairs, said on Israeli television on Sunday, referring to the missile fired at a Syrian mortar battery.
Israel also confronted fire along another one of its border areas on Sunday, when from morning through nightfall more than 50 rockets fired by Palestinian militants from Gaza struck southern Israel. The first heavy barrage came as residents of this rocket-battered town near the Gaza border were getting up to go to work and school.
The prospect of violence flaring with Syria and with militants in Gaza meant that after years of relative quiet along the country's borders, Prime Minister Benjamin Netanyahu finds himself tested on two fronts. Under increasing pressure and with Israelis scheduled to go to the polls in January, the nation's leaders are talking tough and threatening broader action.
"The world needs to understand that Israel will not sit idly by in the face of attempts to attack us," Mr. Netanyahu told his cabinet on Sunday morning. "We are prepared to intensify the response."
But on Sunday, while Israel viewed the fire from Syria as unintentional, though still unacceptable, the rockets from Gaza were deliberately aimed at population centers. Hamas, the Islamic militant group that controls the Palestinian coastal enclave, has claimed credit for participating in several recent rounds of rocket fire.
The latest surge began on Saturday when Palestinian militants fired an antitank missile at an Israeli military jeep patrolling Israel's increasingly volatile border with Gaza, wounding four soldiers. Four Palestinian civilians were killed when Israel returned fire with tank or artillery shells, prompting new rocket fire against southern Israel. At least one Palestinian militant from a rocket-launching squad was killed in an Israeli airstrike.
Responding to years of rocket attacks, Israel carried out a three-week offensive against the militant groups in Gaza in the winter of 2008-9, resulting in an informal and shaky cease-fire. After three civilians were wounded by shrapnel in the Sderot area early Sunday, Silvan Shalom, a vice prime minister from Mr. Netanyahu's conservative Likud Party, said that Israel was "not eager" to embark on another major ground operation in Gaza, but that the military was prepared to act. Yisrael Katz, another Likud minister, called for the liquidation of the Hamas leadership in Gaza and said that Israel should stop supplying the enclave with water, electricity, food and fuel.
In a statement, the defense minister, Ehud Barak, said that the military had been "evaluating a host of options for harsher responses against Hamas and the other terror organizations in Gaza" and that "it is Hamas that will pay the heavy price, a price that will be painful."
Jodi Rudoren contributed reporting from Jerusalem.
This article originally appeared in The New York Times.