TEL AVIV -- The Israeli military said it shot down a drone on Thursday, five nautical miles off the coast of its northern port of Haifa, after tracking it for an hour as it flew south along the Lebanese coast.
"Once we confirmed that it was not a friendly aircraft and it had entered Israeli airspace, F-16 aircraft intercepted it with air-to-air missiles," said Capt. Eytan Buchman, a spokesman for the Israeli military.
Captain Buchman added that questions like whether the drone was armed were being investigated and that the military had not yet confirmed conclusively where the drone had originated.
Israeli suspicions immediately fell on Hezbollah, the militant Shiite organization in Lebanon, which fought with Israel during a monthlong war in 2006, and which Israel regards as a terrorist organization.
The Hezbollah-owned Al-Manar television broadcaster in Lebanon reported the downing of the drone, citing the Israeli military. Later the organization sought to distance itself from any responsibility. "Hezbollah denied that it has sent any drone towards the atmosphere of occupied Palestine," the organization said, using its terminology for Israel, on the Web site of Al-Manar.
In October, after Israel shot down a drone that had flown 35 miles across its southern territory, Hassan Nasrallah, the leader of Hezbollah, boasted that his fighters had assembled and remotely flown the aircraft. He said it had been designed in Iran and assembled by Hezbollah experts in Lebanon. It was Hezbollah's right to deploy drones, he asserted, noting that Israel's military aircraft frequently violated Lebanese airspace, and vowed then that "it was not the first time, and it will not be the last."
The latest incursion comes at a delicate time as Israel warily monitors the civil war in Syria for fear that sophisticated weapons could be transferred from the Syrian army into Hezbollah's hands and taken into Lebanon. Israel has declared that it would not tolerate such a development. In late January, Israeli warplanes struck a convoy of antiaircraft weaponry outside Damascus that American officials said had been headed to the Hezbollah militia in Lebanon.
Prime Minister Benjamin Netanyahu, reacting to the shooting down of the drone, said in a statement: "I view with utmost gravity this attempt to violate our border. We will continue to do everything necessary to safeguard the security of Israel's citizens."
Mr. Netanyahu was informed of the incursion as he was being flown north in a helicopter. The helicopter landed for a short while as the interception was under way, then resumed its flight north.
Jonathan Spyer, a senior research fellow at the Global Research in International Affairs Center at the Interdisciplinary Center in Herzilya, Israel, said he believed the drone was Hezbollah's and was "part of an ongoing process" in which the organization "likes to test out the capabilities" of the Israeli Defense Forces. Mr. Spyer also said he believed the downing of the drone "was not likely to trigger anything major" between the two enemies.
Mr. Spyer, who specializes in Lebanon and Syria, noted that Hezbollah had faced harsh criticism lately at home and in the Arab world for its role in supporting President Bashar al-Assad of Syria, and said the drone could be seen as a reassertion of its core mission: antagonizing Israel.
"To remind everybody that Hezbollah actually is against Israel, to remind everybody that Hezbollah can tweak Israel's nose, is not a bad day's work from a Hezbollah P.R. point of view," he said. "It's a very calibrated move that is designed to make a point without bringing retribution from the I.D.F., which is the last thing Hezbollah wants right now."
Tom Fletcher, the British ambassador to Lebanon, made a similar point in a Twitter post Thursday afternoon: "Last one was at moment when Hizballah faced criticism for support to Assad."
While Israeli officials were quick to denounce the drone in harsh terms, analysts said that Israel's increasing concern about the security of the Syrian border and fear of Syrian weapons being transferred to Hezbollah made a further military action unlikely.
"What I suspect is we won't see a huge Israeli retaliation," said Amos Harel, co-author of a book on Israel's 2006 war with Hezbollah called "34 Days." "If you look closely at what Netanyahu is doing, he's always much more careful than his public talk. I don't think he's into sending military messages right now if he has other options. He's not looking for a confrontation. He's more worried than asking for something like this."
Mr. Harel, a defense analyst for Haaretz, the Israeli daily newspaper, said the crucial question is whether the drone carried only cameras, like the one shot down in October, or weaponry, like at least two sent in 2006. "That's a whole different ballgame," he said. "That would be a direct intervention by Hezbollah and a huge challenge for Israel."
Jodi Rudoren contributed reporting from Jerusalem, and Hwaida Saad from Beirut, Lebanon.
This article originally appeared in The New York Times.