Over the last two years, according to military officials, much Israeli Army training has moved from the southern desert to the Galilee region in the north, where the terrain is similar to that of Lebanon and Syria.

At the same time, the Israeli military is conducting a mostly covert campaign to maintain a qualitative edge over Hezbollah and curb the buildup of the group’s weaponry. Israel has refused to confirm or deny involvement in about half a dozen airstrikes over the past year, mostly in Syrian territory. But Israel’s leaders have said they will act to prevent transfers of sophisticated weapons to Hezbollah from Syria, such as accurate, long-range rockets and shore-to-ship or ground-to-air missiles. Israel is also concerned about Hezbollah’s acquisition of unmanned aerial vehicles, more commonly known as drones or U.A.V.’s.

“A Hezbollah with modern surface-to-air systems, with modern U.A.V.’s, with modern cybercapabilities, well, this is a different Hezbollah,” the senior military official said, one that could have “much more appetite to taste another conflict with Israel.”

In a departure from its usual practice of remaining silent about the Israeli airstrikes, Hezbollah openly accused Israel of striking one of its positions on the Lebanon-Syria border on the night of Feb. 24, and it threatened to retaliate at a time and place of its choosing.

Days later, in another unusual development, Israeli forces in the Golan Heights fired artillery shells at a small squad of men across the Israel-Syria frontier who were said to have been trying to plant an explosive device. The Israeli military described the men as “Hezbollah-affiliated terrorists.” The official Syrian news agency, SANA, said the Israeli fire wounded seven Syrian security personnel and four civilians.

If the men were indeed affiliated with Hezbollah, the episode could indicate that the group has started operating against Israel in a new arena, along the decades-old cease-fire line between Israel and Syria.

Still, many Israeli analysts believe that for Hezbollah, the disadvantages of its engagement in Syria outweigh the advantages, and that there is an upside for Israel.